Older Cat V50c burps 1/4 to 1/2 quart of transmission fluid out of fill tube while parked (not running). Had bent differential yoke/output shaft replaced, and damaged seals on shaft done as well. Trannie started burping oil immediately after. Tech returned sampled, tested, replaced oil, verified oil specs, non-foaming, etc. Tech lowered oil level to minimum on stick thinking it was a capacity/overfill issue. No success. Is there a vent somewhere which could be blocked? Any other possible solutions?