With the Commodore 64 now being well over 30 years old, it is perhaps not surprising that old age is beginning to take its toll. The most common problems in the C64 are a bad 6581 SID chip (no / corrupt audio) or PLA chip (black screen). Other usual suspects are the 6569 VIC-II (video issues), 6510 CPU (no boot, hangs), 6526 CIAs (dead keyboard or serial port). I have sourced as many replacement parts as I can and listed them here. All items are new / unused unless stated.