Konica C35 light meter help?

My first thought is that the zinc air battery is causing the problem. I'm surprised that it has been suggested as suitable. Those batteries deliver a very low current for a long period of time. If you use them momentarily for a higher current than they are designed for, then the voltage drops right down and they take a while to recover. In desperation I used some once in a film SLR camera. I had to wait one minute between shots, though they were powering the shutter too.

Which C35 do you have. The original C35 has no other markings. The C35A has a badge saying 'automatic' on the front. The C35V has a little badge on the front with 'V' on it. The C35FD has 'auto S3' below the Konica nameplate.

Edit: My camera was probably pulling a lot more current from the zinc-airs than the C35. Also you're not supposed to stack them apparently, which I was. They do seem to be powering at least some C35 cameras just fine (see ref).

Apparently A76 alkalines are sometimes used too. The voltage is higher than the original mercury battery so there wil be a risk here. The reference suggests this may be OK provided there is a voltage regulator in the camera. The earlier C35 cameras did not have one.

Hope this helps. If I've just found a bunch of stuff you knew already, my apologies. At least I know a bit more now.

Konica C35

on my sekonic, it always is under a 1/3 stop unde what it should be.
if it reads 6.1 I shoot f8.

I think its failing because of the corroded battery, that may have done some internal damage to the wires, etc. I think your best bet is to get one off of ebay for around 80.00. You could always check your meter readings against your histogram after you take a picture.