I am all finished up rebuilding and putting new seals in my vickers tandem pump part #140 466 15 01. It goes into my 1992 300SD, the issue I'm having is putting the main shaft back into the body of the pump. There are 4 spring loaded dowels that ride on the bearing on the main shaft that I can't figure out how to compress and get the shaft in. The YT videos I've seen use a ZF tandem pump and they put the bearing in first before the shaft, the issue with that is my bearing is held onto the shaft with a snap ring so I can't put it in first, it has to be all together as far as I know. I'm thinking there has to be a special tool I'm missing or some more disassembly, or maybe the bearing doesn't need to be attached to the shaft and the snap ring can be left out? I am lost and my pump is still in pieces, if someone has experience or some insight or ideas on how to get the shaft in I would greatly appreciate it.

These are the dowels I'm referring to

This is how far the main shaft will go without compressing the dowels. Hardly any space.