If you're using a willem programmer then that's 99.9% chance the problem. But even with good name brand programmers every dumper needs 2 different brands if you want to be a decent dumper in the long term. For example a wellon (not willem which is good for nothing) is solid for a lot of newer chips like surface mount flash chips, but occasionally inexplicably problematic on some older and more simple chips and it can't run things like the Charles MacDonald pal adapter correctly. Anyway I know you said besides using multiple programmers but I've seen that solve issue after issue after issue for all the years I've been dumping. Is it giving consistent crcs?