I finally found a cosmetically beautiful MCP 6500 for a good price but it does not work. I have opened it, and there appears to be no battery acid issues. When I press a button, the display will sometimes briefly light up for a few milliseconds on some of the lights. I have measured all of the transistors, and compared with the service manual (my writing in read). Are there any obvious faults that I should be looking for? One thing that puzzles me is that the voltage seemingly stops at one end of D18 whereas there is voltage at both ends of D19. But the diodes both measure find on the board. Any help is appreciated.