Upper oil seal removal in lower unit

I'm looking for some advice on replacing the two oil seals in the top of the lower unit bearing housing. I was replacing my water pump impeller on my '93 vx250 and noticed that the oil seal in the top of the bearing housing, which normally has a spring tensioner around it to maintain a tight seal against the drive shaft, had spring parts instead. I pulled the bearing housing and ordered the replacement seals. Any tips on removing and replacing these seals? There was no water in the lower unit, but there was water between the two seals, so I think I caught it just in time. Thanks!

Also, when replacing, can I assume that I use the same number of shims?

Thanks!

Thanks, it was very easy to do. I used a drill press and socket to press in the new seals, then made sure they were even.