Err you don't want a soldering gun, you want a soldering iron.
No charge if I can't do anything to help just pay return shipping. If I can fix it it'd be $5-10 max.
Somewhat curious if there might be a CIC problem. IIRC SNES games will freeze with communication between the CIC on the cart and inside the SNES are interrupted. Disabling the SNES side of things would likely fix it but it can be tricky for anyone not experienced in lifting pins with a needle.
Thing is if it is a CIC problem using a different SNES might solve the problem. OTOH I've seen corrupted saves have some odd behaviors towards the cartridge itself. Many moons ago I used a "play as Metal Mario" code with my GameShark on Super Smash Bros. After that the game automatically forced you to play as Mario no matter what character you selected. Sadly the only fix was to wipe the save and start from scratch. Not sure if the saves on the cart could cause what you're seeing but it is a possibility albeit unlikely.