A600/M-Tec A630 instability

[a1200]

Being as A600 motherboards are a lot cheaper to replace than the A630, and indeed some A600 accelerators, like the A1200 ones, do have issues with certain motherboards, I would be inclined to replace that first.

In the UK Amiga Retro Experience always sells boards, see:
eBay Link
but I understand NTSC A600s are a little rarer. Even if you have to buy the whole A600 to try it, the results of having a cute 030 powered machine are great see my old A600 here. If you have to get a grubby A600 cheap, then at least you can put the motherboard inside your existing case and you have a spare internal FDD and keyboard. I will put 10 dollars on the motherboard being the problem.

[a1200]

When I had my A600 accelerator I got a blunt slotted screwdriver and gently hit the bottom of the 68000's pins to make the pins form a lip for the accellerator to sit on instead of a smooth drop which the socket cannot "clip" onto.

[a1200]

If you do tweak the 68000 and break it by accident, I do have a shed load of new 68010's which are pin compatible with the 68000. As the 68030 would be doing all the work anyway, the 68010 would be as compatible as the 000.