I would just thank my lucky stars that the thing works at all.

I got a pallet-load of these a few years back. About 85% of them had
some serious problem.
The Fan controller IC tends to burn up real good. The hundreds of
IC's tend to work out of their sockets.

And many issues are not fixable-- there are a passel of adjustments
that are "factory-only",
or require a reburn of the calibration roms.