I've found another Timex Sinclair 1016 RAM pack, it's in good condition but it seems to have had a problem with one of the 74LS157 chips necessitating a replacement.
The problem seems to have caused the DC-DC converter coil to overheat and the enamel on the inner windings has darkened.
- Timex Sinclair 1016 component side
- Solder side
This RAM pack might make a suitable candidate for a 64K expansion, which makes the DC-DC converter redundant because 4164 DRAMs use 5V so I'd save myself the bother of rewinding the coil.
Rewinding a coil that's overheated is a good idea but care must be taken.
I've done it a few times with Spectrum coils, you desolder the wires and replace with an equal length of the same gauge of enamelled copper wire taking care to avoid scraping any enamel off the wire.
I've not yet tested the RAM pack to see if it works.