Canon AT-1

On a lark, I thought I would compare the meters of my two (2) AT-1 Bodies.
What I found was that the battery check in one of them reads a lot lower.
If I am reading the manual correctly, the needle should jump way to the top, which it does on one body.
The other, the needle sits in about the middle position.
I used the same battery for both, and checked it twice.
Is this a user fixable problem.?
Calibration problem.?
Bad meter.?
Thank You

Battery check switch, battery contact problems, battery check circuitry are the probable problem areas.
To test the meters put the same lens on both bodies and meter a gray card in the same light, both bodies should give the same reading. If you do not have a gray card read the scene with the camera pointed at the same point in the scene. Meter in shade, normal daylight, and bright sun.
Different lens of the same marked focal length can read a fraction of a stop different from one another.

Yeah...sorry, I forgot to add.......I metered both cameras with same battery and same lens, in 2 different situations.
The camera with the "bad" battery check reads about 1-1/2 to 2 stops lower.
Both the needle and the straight lever read lower in the meter than the camera with the good battery check.
Tech time I suppose...

Time to see a camera tech or use an external meter.