Yep, schematic does not seem available on the web... for free.  Did find it here for $15 (gs-100D, download):
http://www.schematicconnection.com/store/asp/product.asp?recorprod=1&product=355&cat=127&ph=&keywords=&recor=&SearchFor=&PT_ID=
  Otherwise, they were apparently bought out by Fender, so you could contact Fender & see if they have them.

  That's a GS100 chassis.  Did someone stick it in a GV60 cabinet?  Where does it say GV60 on it?

  Also spray some cleaner into the FX return jack, then plug a cord in and out of it a few times to work the cleaner in.  There is a switch in the return jack that closes when you are NOT using the FX loop.  If the switch gets dirty/oxidized, the amp will cut in and out.  Plugging a cord between the send and return bypassed the return jacks internal switch, temporarily solving the problem.
  If you are lucky, cleaning the pots will solve the "breathing" noise, otherwise it may be a noisy semiconductor (transistor or IC).  In this case, finding which semiconductor is the noisy one can sometimes be difficult.

 When I think of DSP for earlier stuff I think of eprom's etc. with stickers on them that stated their version number.  One of the first pieces of guitar type gear that could be "upgraded" software wise via eprom that I recall was the ADA MP1.
  If anyone remembers the pages of factory mods those went through, it was quite extensive.
Hope that counts even though it was only a preamp.

  Measuring the resistors in circuit can give lower readings due to parallel resistances in the circuit.  To properly measure them you need to disconnect at least one side of the resistor from the circuit.
  I think yours are probably ok.  If you measure them in circuit and get a HIGHER reading than they should be, then they are suspect.

  Those ribbon wires are pushed into those connectors.  The connector is spring loaded, you push down on the spring loaded side and pull the ribbon cable out.  The insulation is stripped back a bit so it is just bare wires pushed into the connector.

  It looks like the board with the "over and under" wiring is a newer version with extra holes drilled.  Your board does not appear to have the extra holes so you won't be able to do that.  What you can do is add a bit of support where the wires meet the board by using some silicone or hot glue.  At least that will keep them from flexing right where they meet the board.
 

  It is not necessary to desolder the wires from all the pots.  You can remove the knobs and the nuts holding the pots to the chassis.  Then push the pots into the amp.  If you are careful you will be able to flip the board without breaking more wires.
  If the wire is solid core, you may want to use stranded wire for replacement as it will probably take more flexing before it breaks.

  Looks to be very straightforward as far as where the wires go.
If you haven't done something like this before, the trick will be to get the board loose so you can turn it over to solder the wire back to it. 

 Another thing to try: remove the power tubes and measure the grid voltages (pin5 at each output tube socket).
This  should tell you whether the problem is at one socket or both.  You should get your -35VDC at both sockets and it should stay stable.
  If the problem is at both sockets you may have a bad connection somewhere common to both, such as P18 or P19. 
  If it is a bad coupling cap, then I would expect the problem to be more evident at one socket with the tubes removed.

Quote from: Harley on January 30, 2013, 08:24:57 PM
the circuit board was broken where the effects switch is located.  I fixed this with super glue.  Could super glue on top of the copper circuitry cause an issue?

If the board is cracked where there is copper circuitry (traces), then super glue will not fix it.  You must inspect the crack with a magnifier and repair any cracked traces with jumper wires. 
  It is possible flexing of the board when you had it out did further damage to the cracked area so you must make sure all the cracked traces are repaired.
  As far as the smoke, that sounds like a different problem.  If you were running the amp on the bench without the heatsink all bolted to the chassis it is possible some of the output devices may have fried.

 Well, if the heatsink screws connect to traces, then you are probably ok.  Remove those particular screws and if your transistors are all insulated from the heatsink you should be good.
  Sounds like you have already done this but doesn't hurt to double check.
Edit:  Looking again, it appears the heatsink is grounded (it screws to chassis), so you shouldn't have any collectors or parts of the bridge rectifier shorted to the heatsink.
  You appear to have shorts from both + and - rails to ground.   Find the source of your shorts.

  You must sort out the transistors insulation from the heatsink.  The transistors meant to be insulated should have some kind of mica spacer or silpad, along with some kind of plastic bushing for the screws.
  If all the transistors are insulated, then you should not have any collectors shorted to the heatsink when they are all tightened (as the heatsink itself is floating, correct?).  If they all have insulators, one of them must be cracked or damaged.  Find out which one.

  Enzo, the eighty-five, studio 85 and deluxe 85 are essentially the same, maybe different speakers.

The pre-out jack is 025929, which is now 099-0912-000.
The footswitch is 002-8122-000, which is now 099-4056-000.  It is also used in the Princeton112, Deluxe112, Blues Deville, Blues Deluxe, and others.

For amplifier settings, you may find tips in the owners manual: http://digilander.libero.it/BLJ/documenti/Fender85-2.pdf