Need Help!- boss axis problem

[loose1]

I have a early 80's boss series 1, I don't know what boss version it is. It has a machine master control. My problem is the y axis sometimes doesn't move but it shows movement on the screen. I did some digging on this site and found the the transistors are known to cause this problem. So I switched the x and y boards and it still does the same thing and I don't know what to do next. I don't have any knowledge working on computers so dummy terms would be helpful.
Thanks, Matt

[kewl_cat]

The first thing you need is a manual from machinemanuals.net.
Second, the transistors are set up as darlington pairs. One transistor on the smd board along with transistor on the heat sinks. You are looking at the wrong transistors on the boards. There are 3 heat sinks located under the smd boards. They are labeled x, y & z. You can test them like a diode. Switch the leads on the checker and you will see a different reading. You will probably find one that reads the same both ways. That would be the bad one. I buy the 2n6547 from Futurlec or get them off ebay