Thanks Roly. This was a good exercise for a beginner like myself. I stripped down all transistors and checked them out of circuit. I found that Q309 was faulty. Upon replacement, I began reinstalling the output transistors as you described. In the end, I now have 4.6 MV at R334 which is within the 0.1V you specified,right? I also rechecked the B+/B- values at D418 and now have +/- 38V and at CN 502/501 (I think the supply for the power amp) I have +/- 42V. While I was poking around, I metered at R342 and R346 ( thinking I would find 15V) and found 38V. I'm trying to follow the schematic and test values.
     As for IC401, I noticed it was very loose. I took it out  and tested it. I wired two 9V batteries in series for roughly 17V  and wired to the input and ground respectively. Woo she get hot yes! Measured output was 15V so it is OK.
     Do these values sound acceptable and are there  more tests I can or should perform.

   Fired up the power amp and it didn't explode so I'm happy for that. I metered TP1 and TP2 and had 38 v. I also tested R334 and had the same. When I say I metered them, I put the pos. lead on TP1/2 and neg lead to ground. For R334, I did the same, one lead on the side and one to ground. My impression was that I should have +/- 15 v at the TPs, and I guess since I have 38 v at R334 that's the reason I don't? More digging.

    Ok , so my transistors came and everything checks out. Got it installed on the board and now the moment of truth. The problem I have, is that the power amp has a relay switch as some sort of safety. When I use my limiter, the relay won't click over. I metered  the limiter and with a 40 watt bulb it is sending 65 v  ac . I then metered D401 and CN502 for B+ and B- voltages and got 63 and -63 respectively.( I think on the scheme D401 is D418). I stopped there as I found a shoddy regulater at IC401. What can I do to power up the power amp with low voltage to make sure everything's on the level? Jumper the relay and use a limiter?

   Point taken. It seems I was trying so hard to find the exact part that I overlooked the obvious. When searching data sheets I noticed some were close but one or two of the parameters were off. I didn't know which to hold and which weren't as critical for clean operation. Again, I still only searched a specific part,not on specs alone. I'll chalk this one up. So much to learn.

   Hey Gonz. Yes I do have a limiter that I intend to use when the time comes. Finding the part in question, however, is proving to be a little overwhelming. I have a RFQ with American Micro semiconductor for an exact replacement ( 2SA968A-Y props to Enzo). We'll see how that pans out. I also have options with Toshiba, Ali express and Suburban electronics. Thanks for the link,also.


Edit: just ordered matched pair  from an eBay sight. Fingers crossed.

   Thanks Enzo. The other components seem fine. I'm using a DMM on continuity and on diode test and the readings for Q314,16,18,20 are comparable to Q313,15,17,19 respectively. I didnt want to power it up until I got that part for fear of doing more damage. I'm hoping that is all I need
 
    As for a schematic I don't have one, I'm simply reading the PCB for component designations. I've tried to look at different schemes but it doesn't help much,as I dont know how to read  them yet. Thank you for your guidance.

   Hi everyone. I have a hartke 3500 that is need of a component. I'm still learning so thank you for bearing with me.

   The area in question is the power amp I think. The part number from the board is Q 310 ,and I'm pretty sure its a transistor. Its totally destroyed and in need of replacement. The numbers off of the part itself are:          K
                                                                                                 A968A
                                                                                                 Y  241
  I haven't had much luck on the net. So I'm asking where I could go to get that part or its equivalent. Any help will be appreciated.