I still think your best route is to search out a Mac 512K or Mac Plus, and swap in its analog board for yours. I just looked on eBay UK, and a Plus can be had for as little as 24 pounds.
Failing that - you need to concentrate on the analog board, and isolate one problem at a time. I would suggest taking the logic board out and putting it away on a shelf. You don't want to confuse things by taking floppy port measurements, if there's potentially a problem with the logic board *and* the analog board. So you can put away the logic board, and take your measurements from the motherboard connector on the analog board.
Next, not to be rude, but are you sure you're using the voltmeter correctly? The readings you listed don't make a lot of sense, and you put question marks after others. Try using the voltmeter to measure some unrelated stuff on another computer, and make sure the voltages check out OK, to be sure the voltmeter is set up correctly and you're getting the expected numbers.
Now if you're still getting wacky voltages from the analog board, you can continue following the steps from Pina's book, or just go ahead and replace all the capacitors. These seem to be the parts that typically fail - though I can't say I've done this personally. Most advice you find about repairing the Mac Plus or Mac 512K analog board should also apply to your 128K.
Lastly, try removing the PRAM battery, just to rule that out.
Failing that - you need to concentrate on the analog board, and isolate one problem at a time. I would suggest taking the logic board out and putting it away on a shelf. You don't want to confuse things by taking floppy port measurements, if there's potentially a problem with the logic board *and* the analog board. So you can put away the logic board, and take your measurements from the motherboard connector on the analog board.
Next, not to be rude, but are you sure you're using the voltmeter correctly? The readings you listed don't make a lot of sense, and you put question marks after others. Try using the voltmeter to measure some unrelated stuff on another computer, and make sure the voltages check out OK, to be sure the voltmeter is set up correctly and you're getting the expected numbers.
Now if you're still getting wacky voltages from the analog board, you can continue following the steps from Pina's book, or just go ahead and replace all the capacitors. These seem to be the parts that typically fail - though I can't say I've done this personally. Most advice you find about repairing the Mac Plus or Mac 512K analog board should also apply to your 128K.
Lastly, try removing the PRAM battery, just to rule that out.