Contour Enthusiasts Group Archives Forums Modifications Duratec Maintenance went to pull the axle, and... WHOOPS!!

Examine the snap ring to make sure its not nicked or bent if you didn't put on a new one.
lubricate it with atf or something as well as the area that rides the axle seal.
Use a small wire brush or even an old toothbrush with some oil to dlean out the splines if there is any sign of reddish oxidation or other crude.

Othewise, just get it started to where it is splined, keep it very straigh and grab the shaft and give a couple gentle taps forward to compress the c-clip and get it to slide in. Since you know the tripod joint slides it will bang into the back of the joint housing. It isn't the best way, but since you've already put the boot on then you will damage the boot with a hammer. If you tap it gently enough you won't damage the joint and it'll go in. If it doesn't, remove the boot clamp, tap in the inner joint until it slides in, then reclamp the boot down.