Originally Posted by brewer79
A Is this going to be a major fix?
B The second problem involves a three way switch downstairs.
Less so if you know what all else is on the same breaker. You might also start looking for a tripped GFCI somewhere.B
Three way switches have Phantom Voltages https://www.nema.org/Technical/Documents/Bull_88_reaffirmed_12_15_11.pdf
which will really confuse because the voltage you read depends on the type of meter you use.
I recommend a 120v, 100w or larger incand bulb in a socket with pigtail leads as a tester. Almost any hardware store carries this item.
If you put your multimeter across the bulb you have made a low impedance meter as mentioned in the link.
You'll need to figure out which of the three switch terminals in the switches are the wiper/common terminals and which are the switched terminals. Usually the wiper screw is a different color than the other two screws.
If you don't like troubleshooting of the very tedious kind, take a gamble and replace both switches. But, I recommend the troubleshooting!
BTW, test each switch before install with a multimeter.
Good problem, in any case.