Seized X-9 Pulley anyone?

I had the same problem with mine.

I ran into some nasty weather and decided to tear down mine - degreased the bearing and re-greased. Some helpful advice - don't degrease with simple green - too corrosive -- just use wd-40. I wrenched and wrenched on mine and could not get them to budge. I called sram -- they have a 1-800 number -- the guy I talked to said they should break free (they are normal thread). He said I guess they got a a little locktite happy during assembly. He told me that if I ended up stripping one he would send me a new derailleur. Mine eventually broke loose so I was not able to see how serious the guy was. Try to get some extra leverage on the handle of the allen wrench. Otherwise call sram or I guess you might have to drill it out.

Yep, I've had them get stuck too. They went away from a roller bearing on the upper pulley for some reason and just use a huge steel drum that the plastic jockey wheel slides on. Heavy and weird. It is easy to lube, but there is no lube "reservoir" in there to replenish when things get washed out, and the steel rusts and grabs the jockey wheel. Not a terrible design, just not as nice as the bearings. At least make it ceramic like the old Shimano or something...

Any upgrades for this or any tips on maintaining them?

I mentioned this problem at their european ride camp this year after mine siezed in the winter mud last year. They didn't dismiss the it as such but suggested using a fairly viscous (runny) grease when re building the pulleys. (I now use Manitou M-prep which seems fairly durable) I have also found that if you round an allen head off, you can often still remove it if you use the biggest Torx fitting that will fit into the rounded head. Also a bit of boiling water over the siezed Loctite will enable you to crack the seal.
Good luck