I've got an old Reliable Elevator acting up. Had a blown mainline fuse and after replacing it the car always takes off and goes to the fourth floor. It's not the hall button or the car button.

I have no documentation available for this controller so I'd greatly appreciate any help.

What type control ? Relay type? How old ?
The controller with square 6 pole DT 48 volt relays is common. May have welded contact.
I have some prints scanned..

Prior to the fuse blowing, it never went to four by itself?
Fourth floor is top?
Will it run normally after it gets to four?
Do doors cycle when it gets to four?
Have you, just prior to, or after the fuse blew, removed and replaced any of those delicate Midtex ice cube relays?
Sounds like a selector problem...either floor relay or bad latch relay. Step up/DZ optical inductor could be bad too. I recall a stepper card in the controller, and some floor level sensor card in the COP.

Caution: When removing and reinserting those Midtex ice cube relays....you’ll never know if you’ve bent a contact pin until your trouble gets worse...good luck.