Jack, its not too difficult, but it can sometimes be a pain. (that makes sense right?)
Basically, push the PTO shaft out. Once you do that, you will see the shoulder in between the two bearings. This is an important part of the PTO, as it is a clearance fit with the PTO shaft, and helps seal the engine. Basically, you dont want to scratch or damage this area of the PTO housing. I usually rapidly heat the housing with a torch, then smack it down on two wooden blocks that the bearings will fall between. They usually fall out fairly easily with a few smacks. Basically the flange portion of the PTO housing, the part that bolts to the case, is what hits the wooden blocks. the bearing should have a place to fall out. Sometimes there is enough of a lip on the inner bearing race to use a small driver to tap the bearing out. To install, I do the opposite more or less. Heat up the housing, and the bearings will fall in fairly easily. They need to be perfectly seated though, so take care to make sure they are flush in the housing.
Or, you can send the PTO and bearings to me (im back in the states now), and I will change them out. No charge, and it wont take as long as the muffler.
if you dont feel like messing with it.
~James