9V battery box & motor troubleshooting?

[Xfing]

I picked up a used 8064 set from 1991 on Bricklink the other day. Sadly it turned out the battery box was completely busted - borderline unopenable and when I managed to open it, it was full of rusted, leaked batteries like no one touched the thing for at least 5 years. I was on a good track to salvaging the box with some vinegar soaking and filing off the residue, but sadly one of the spacer plates snapped off, at which point I gave up and ordered a new box on Bricklink. The new one is clean enough, the contacts on it and on the cables look alright and the motor is intact - yet somehow I can't get the motor to start in any way. I put 6 rechargeable 1,2V batts into the box (inserted correctly), and while I understand 1,2V is not as fast as 1,5V, to my understanding the motor should still work. It spins fine, all the contacts look clean, the battery box buttons click properly when pressed, so I'm at a loss what could be the issue. Any advice would be welcome, if needed I can put up photos.

Edited November 27, 2025 by Xfing

[Xfing]

Ok, just a heads up, I was able to narrow down the problem. The lower rear left battery wasn't making contact. Those Energizer rechargeables have really short plus nubs and apparently it just wasn't reaching the plate. It's not a problem anywhere else in the box though, for some reason. A temporary solution is just putting a thin aluminum foil strip between the nub and the contact, which does manage to close the circuit. What should I do for a more permanent solution, solder on a thin copper plate or some such? The minus side spring is fairly strong so it is pressing the battery adequately against the plus plate, but for some reason it just couldn't reach. I know I could just use different batteries, but I've got 12 of those Energizer ones, just enough for rotation for recharging, so it'd kinda suck to have to buy a new set now.

Edited November 27, 2025 by Xfing

[Toastie]

18 minutes ago, Xfing said:

What should I do for a more permanent solution, solder on a thin copper plate or some such?

This is really a special case ... had same issues on some cheap outdoor "solar" lamps. Aluminum foil sounds like tiny tolerances - what about simply applying a layer of (maybe silver based) solder on the positive contact? This should bridge the tiny gap as well as providing some durability. And you can apply simply "more" should the problem not go away.

Best
Thorsten 

[Xfing]

30 minutes ago, Toastie said:

This is really a special case ... had same issues on some cheap outdoor "solar" lamps. Aluminum foil sounds like tiny tolerances - what about simply applying a layer of (maybe silver based) solder on the positive contact? This should bridge the tiny gap as well as providing some durability. And you can apply simply "more" should the problem not go away.

Best
Thorsten 

Yeah, thanks for the suggestion, I might do that. I actually went and gave that contact a good filing with sandpaper and apparently now the circuit finally closes with no extra hassle. I was super worried, so it was pretty lucky to discover that lack of contact with one of the plates was the problem!