Canon New F-1 Slow Speeds Shutter Problem

Hey everyone. I recently got my hands on a Canon New F-1. At the shop I tested out the camera, finder and everything else was clean, and it seemed to be working well. All the mechanical speeds from 1/125 - 1/2000 fired no problem, no slow shutter/stuck. I didn't have a battery with me at the time, nor did the shop, so I couldn't test the electronically dependant slower speeds 1/60 - 8. The price was good so I bought it anyways. Went home, popped in a new battery, self-timer works, battery indicator indicates full power, shutter still fires fine, but none of the slower speeds 1/60 - 8 fired at the right speeds. All fired the same at like 1/125. I feel the electronics have stopped working to control the slower speeds and hold the shutter open for longer, but I'm not sure. Searching the internet and doesn't seem that other people online have had this issue, mostly stuck/slow shutters, or with battery the shutter won't fire. Does anyone know about this issue, or know if it's repairable? Any insight or advice would be helpful, thanks!

Never have experienced this issue myself but AFAIK could be an issue with the resistor board, contacts between the main PCB and the resistor board, release magnet or transistor, bulb switch. Checking any of those requires different levels of disassembly. Repair could range from cleaning contacts to replacing parts you can only source from another New F-1 body. Cost of repair may range from reasonable to uneconomic. It may be better to return it or sell it for parts.