I also took mine apart because it only charges up to 94% (~81V) anymore, since a few weeks. I analyzed the secondary part to some extend and drew this schematic.

What I learned: there is no communication over the many plug contacts. There is only pin3 drawn to ground to signal the bike not to drive away.

The charger senses the battery voltage beforehand and enables its transverter and the output relais only when it senses a high enough voltage. The output capacitors get slowly charged from the battery, that prevents sparking when beeing plugged in.

The output diodes on primitive heatsinks get quite hot when operated in air, heat conductivity of the potting material will not be great either, but noone notices. The whole charger cannot be very efficient when that much heat is produced. It would not be expensive to use FETs instead and build a synchronous rectifier.

It uses a separate transverter to power everything secondary with 14V.

I couldn't solve my initial problem so far, because the voltage sensing is done on the vertical PCB that is too cumbersome to access and soldered in. I can maybe manipulate the sensed voltage going to the PCB.

I admit it's kinda rewarding to pluck out the crumbling potting material.