Thanks everyone. I put the 10uf cap in and its doing great.  Love the gain sound actually. 
I put it in a 221x150x63.5mm case that I had from mouser. Just want to really thank everyone for this forum and this cool project.

Thanks for the clear explanation and comparisons joecool85.  I'll keep playing around and digest the circuit more to try and understand what I'm doing. Always learning. 

Thanks, I'll try that and see how that sounds.

I got the kit that came with the 8 ohm speaker.  All assembled and currently powered with a 9-volt battery.  It seems I have to have the volume absolutely cranked to be heard over the guitar strings themselves. Turning the gain up obviously gets past this a bit.
I tried to use a 12 volt DC wall plug but that introduced a ton of hum into the amp.
What are you using as power for this little guy? Would an A23 battery work?
Thanks

Got mine too.  Everything looks great and I'm excited to get started working on it this weekend. Thank you for such a cool project.

Hey everyone, thanks for all the advice. I made a light bulb limiter and installed new TO247s for the pairs of darlingtons. Everything had been going strong now for the past week or so of playing. I had the reverb tank unplugged and noticed that the hiss-bang isn't there when turning the and off. Also the constant kind of low static buzz behind everything once you get past volume 2 remains. But I used a little patch cable to go from the effects send to return and now can get a pretty good clean volume before it buzzes if I set the effects return to 5ish. But! The key is that it's working great for me. Than you everyone for your help!

Ok, can do. I was kind of worried about other issues too but was hoping that since it was working up until I pulled the old transistor that it was isolated to only that component. But perhaps I have created more problems than I solved.

Thanks all.  Going to order the TO247 and put those in place of the TO218.  Get it back functioning at least and put it to the side. I'm in a position now where a new amp isn't out of the picture so I'm not too worried about this one, only want to keep it running for sentimental reasons.

Quote from: tonyharker on April 27, 2020, 02:14:16 PM
Did you remember to isolate the transistor tab from the heatsink?

I re-used the little clear plastic thing that was between the transistor and the heat sink. So... I think so but not sure.

Quote from: Enzo on April 27, 2020, 06:07:12 PM
I would never buy transistors from Amazon, any more than I'd buy them from ebay.

What is wrong with using the TO247?   There should be plenty of room on the heat sink.  Might need to get larger insulating wafers due to the slightly larger size.

I think you are confirming what I just wasn't 100% sure of.  TO247 is the equivalent of TO218.  Not until this morning did I really understand that. So I can get TIP142 and TIP147 from say mouser.com and those will be the same footprint basically.

QuoteNot sure why change R172/173, they should run a bit cooler than 100 ohm.

I'm not sure either. Elsewhere on the internet, maybe even this forum, someone suggested upping those to 240ohm but I don't know what that would change. I think they then came back and said nothing changed.

Here is the offending darlington that was apparently working fine but I couldn't leave well enough alone

TLDR: Where can I find the replacements for TIP147 and TIP142 in TO-218 cases now that those aren't made? Ones ordered from Amazon have shorted twice.

I have a Fender Performer 1000 that has been chugging along since I got it in '95.  Its always had the crazy loud "fizzt-POP" on shutting it off, and the background buzz whenever it is on. But these were mild issues for a 3 chord electric guitar player, I assumed all loud guitar amps just had that background fuzzy grumble and when you played notes on the clean channel they sounded clean, things on the two distortion channels sounded distorted and ncie. A friend brought over his newer amp though and it is quiet, doesn't bang when turning off.  So I read tons of forums and cracked it open to see what I could see. Since things were cheap and the Service Manual pdf https://drive.google.com/open?id=0B3nyYPooVy9baDB4LUNBV29aREE going around for this amp included Tech Notes I thought maybe making those changes and replacing/cleaning pots would fix those issues. There was a cap at C68 that had broken its solder so I also fixed that.
During this work I saw that the darlington at Q14 looked super janky with leads soldered at right angles onto the existing leads so they could reach the board. The large caps at C71 and C72 were much skinnier than the white outlines on the board and taller than anything I could find online, which I assume means they had been replaced, and the resistors at R172 and R173 were 120ohms as opposed to 100ohms that the specs showed. So this means someone had worked on this thing within the year or two between manufacture and the time I got the amp!  I thought that while I had the board out I should replace these things since I like everything looking clean and to spec. I made all the tech note changes and replaced the caps and everything sounded... well fine, same as before. Oh well might as well replace the transistors. 
Well, those aren't made anymore.  I ordered some TIP147 in TO-218 size off Amazon since they aren't on mouser and it played well for about 60 seconds before blowing one.  I was getting -40 DC on the white output wire and it was reading as "two diodes" as opposed to "transistor" according to my little testing device.  The other three, the two TIP142, and the other TIP147 read as "transistors". Replaced with another from Amazon and same thing. Fine for a few seconds then blew.
So did I get bad transistors from Amazon?  Should I suck it up and put the original one back in?  Is it TO-247 I should buy? Maybe there is something I broke earlier in the circuit that's causing a coincidental fail of the transistors? It smelled hot when it was on so maybe lack of new thermal grease made them overheat and they were actually fine? Thanks for any help.