front bearing
 

How difficult is it to change the front bearing in a trx 3.3? It has been running wierd and I noticed that the front bearing is dripping, so I assume it has a air leak. Also, on the Traxxas forum, they said that Traxxas recommends not sealing their motors, should I do it anyway?

If is only dripping its fine, now if you have residue all over the chassis around the clutch and front of the engine there's a problem.
The trx engines are made to have a small bit of oil leak out of the front bearing, theres actually an oil port for the front bearing drilled through the case near the carb.

Any way to replace it you have to completely dissemble the engine and heat crankcase up to 250-300* from there you should be able to push the bearing out with a chock of wood and a hammer repeat the process to get it back in.

Before going through all the hassle of replacing the bearing, I would just buy a crankcase with bearings of e-bay. There are a few "chop shops" that strip new engines and sell them off. Like this one here.

And in regards to sealing the engine, I've never had the need to seal any of my traxxas engines. I just installed new o-rings and never had any issues. There are plenty of other people who sealed their engines, and it worked for them. So if it would make you feel better, seal the sucker up.;)