I have a beautiful HP-25 (aren't they all?) with problems. It turns on and will accept numbers fine and actually programs fine. It pauses briefly and shows 0.000000000 and freezes if I try to do anything with the stack: enter, operators, etc.
I have replaced the ACT and tried Katie's 20K resistor fix with no luck.
What's next? It seems as if it would be a chip problem, and there's only two main chips left to swap...
Thank you, smart people!