Hi all, I have a couple of old 28Xs (16F873) that I cannot download a program to, or check the firmware of. Any other chip is fine - 08M, 18X, 28X1, etc. But not these 2 28Xs I've had sitting in the box for a while. I can program an 18X, fine, then try the 28X, no response, 18X again, fine...