I've had mine for 2 months. Lucky for me it was working when I got it, then I started breaking it when I tried a LED uprade. I broke some solder joints in the process. Also found a few light diodes completly missing. This is my 5th early 80's machine. They all had issues. I think the best thing to do is gather all the information you can (schematics and user guide) and never troubleshoot while tired or angry. If you can afford it, all the boards are available and most have been redesigned. Although board replacement doesn't fix bad wiring. Test, read, Test, read, and so forth. Check prices on BK. It's worth it!