I'm in the process of repairing a portable Tektronix 214. I disassembled the scope and removed the batteries. Then I powered it directly with a two 6 volt sources and it seems to work, although there might be some connection problems while disassembled.
So I set about getting replacement batteries for the scope. It originally took two Ax5 NiCd packs, but I settled for AA for cost reasons. I had a local shop weld the NiCds because I have been told that soldering directly to NiCds is inadvisable because of reliability problems that can be introduced if the nylon seal is over-heated.
I didn't realize until I got the new packs home, but the technician did not weld to a hanging solder tab. Instead he cut a tiny solder tab that just covers the head of the battery and soldered directly to the top. I fail to see how this is thermally distinct from soldering directly to the battery.
I have included detailed pictures of the scope, the original packs, the new packs, and some diagrams I drew at this link:
https://imgur.com/a/1sSIH3a.
Do I need to have these packs remade? I do not plan on opening this unit again after the repair, so I will have no way to monitor corrosion or other problems.