Not strange at all.
As said before, even on this thread, the 8375 Agnus chips are hard-coded to either PAL or NTSC. Also, you can only swap a -11 type Agnus (NTSC) for a -10 Agnus (PAL). Another type of Agnus will not work at all as they have different pinouts. Period.
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Now, for the battery leakage, drop some lemon juice or spirit vinegar over the affected area, let it over for a few minutes, absorb the moist and clean the area with IPA and cotton buds.
If a trace is exposed, put some transparent nail varnish over it to protect the area.
