TL-super light meter

Hello martintenbones, and welcome to the forum! As I'm still on my extended holiday, I'm away from my TL-Super to check it physically, but maybe I can offer some observations and a few things to try.

The TL-Super was introduced in 1966 and had a fairly short run, so there's plenty of succeeding years for some oxidation to accumulate throughout the electronic chain. You might refer to the camera's assembly manual listed in this thread to see what possible contacts may be fouled and what can be 'exercised' with a bit of friction after repeated use (i.e., speed/ASA dials, on/off switch, etc.) before resorting to opening the body for actual cleaning. At least that might pinpoint a specific component that's causing any issue - if it's a matter of dirty or missing contact points.

On occasion I've needed to insert a few bits of folded tinfoil along with cell batteries as modern battery casings aren't always perfect fits anymore. It might be worth a minute to see if some extra material will ensure full and consistent contact.

If you don't have a printed copy, grab a copy of the manual here, and check procedures and settings to make sure you haven't missed something. As this is a TTL metering camera, it's worth checking if a DoF preview is required to get a proper meter reading.