Fortunately, I seldom have problems with my equipment. OK, now and then you'll have the occasional software challenge of getting things working correctly, but I haven't had any serious hardware failures that couldn't be fixed. Once I had one of my voice boards not working on the Rhodes Chroma. The reseller nearby happened to have another Chroma, so I was able to exchange a voice board.
I recently had a problem with the voice board of my DSI Prophet 08. Voices 3 and 4 were not working. I could tell by looking at the voice LED's not coming on when playing. A week ago I send a mail to DSI and got response the same day. DSI offered to switch voice boards, so after paying $100 they shipped the board to Europe, which I received 3 days later. I opened up the Prophet, exchanged the voice boards, put the top back on again, switched on the Prophet 08, calibrated the filters, and presto! Back on track again, perfect!. When sending back the old voice board $75 will be returned.
What a great service! Indeed a big thumbs up for the people at Dave Smith Instruments! Now I can enjoy one of the best analog synths again. Great!