Bath fan dual switch gone bad. Pic shows bad one on left. On right is just the first switch I saw at lowes so I grabbed it. House is old fusebox shit. No grounds. Looks to me the power (black) is coming in to one switch and then jumpered to the second. Then the common (white) is going back to ground via the lone black wire. Y'all see it? Can I make this new switch work?
Your neutrals are up in the box in the fan, thats how old houses are wired usually. Looks like what you got is a hot and 2 switch legs there. Yes you should be able to make that switch work. Does the fan not work when the light is off? That's what it looks like it would be wired as.
Definitely get a voltage tester .. only $ 7.00- 20.00 bucks . Best way to be sure which is hot . Who knows how " Dern" wired it back in the day.
Only a wet finger, make sure the floor wet all around you as well. I’d also switch the breaker to at least a 30 amp before testing. . I hate electrical work, scares the crap out of me.
Those are old switches, called "despard". You could buy switches, outlets and indicator lights and build your own multi-unit combo. Pretty much these went away in the early 1970's. Now to the issue: First, figure out which fuse feeds that switch, and remove it. Don't work on hot wires. From the pic, it looks to me like the white wire is the hot wire to both switches. That would go to the black screw on the new switch. The other two black wires are the lines to the light and fan, and go to the screws on the other side of the new switch. After connecting the wires to the new switch, put the fuse back in and test. If all is good, turn the power back off, then put the new switch back in the box. I like to put a single wrap of electrical tape around the switch to cover the terminal screws to avoid sparking as you put it back, or if the switch moves a bit in the box. If the white wire actually is the hot, then all will be well. If one of the black wires is the hot, then one switch will need to be on to allow the other switch to work. Turn off the power (remove the fuse) & swap the white wire and the black wire from the first switch (the one that will enable the second switch) and all will be good. Good luck. If you scare yourself, call an electrician.