5 Speed Snap Ring Install

[Nanonevol]

Rebuilding the Spider 5 speed. These two snap rings, one on the input shaft, the other on the main shaft seem impossible to get to fully snap into the grooves. Both hold parts on the shaft and are topped with a convex washer.

Any advice on how to snap these in? I'm tempted to grind the snap ring thinner....
Never mind, got it. Drove it in with a drift.