So I found a Bosch power drill in the trash and I took it upon myself to refurbish it for fun and learning.
Turns out I can't even disassemble it all the way. I'm trying to separate the gearbox from the plastic housing but I'm failing. What I gather from the diagram is that there is a lock washer (is that the correct term? something to secure the parts in place) underneath the gears, but how am I supposed to get to it? Pic related. Video is here but the guy does not take the gearbox apart. https://www.youtube.com/watch?v=rnstC7943a0
Snap ring would be the term for that kind of clip.
Looking at the diagram, the thrust bearing is most likely a press fit to the shaft or just wedged on there really well by grease and age. The snap rings are at the wrong end to be holding the gears, note how the shaft gets larger in diameter on the snap ring side, so the gears can't go that direction to come off. All the gears should slide off the end in the picture though. The snap rings look to hold the shaft in place in the housing(external snap ring) and the shaft in the bearing so it can't slide forward(internal snap ring). They would come off after the gears are removed to free the shaft.
>>2995165 I used a rubber mallet on the threaded part where the chuck was on but the gears at the other end didn't budge. Maybe I didn't use enough force, after all I didn't know if that was the right approach. I'll try again tomorrow. Alternatively would a bearing removal tool like pic related work too?