2003 Shifting hard

[BB2000]

Hey all! I have been experiencing some gear shifting problems with my '03 convertible. It's an auto trans, but when it shifts gears (both up and down) it jerks to some degree, sometimes really noticeably and sometimes not so much. I'm hoping that maybe it's just the crappy gas I use sometimes; I filled it up today with the expensive grade at a Shell station and it seems to have calmed down quite a bit. Could it be something more serious? Obviously can't check the tranny fluid without letting the idiots at the dealership assault my wallet. My baby just hit 100,000 so I'm concerned that she's getting old and tired. I try to take good care of her on a budget. Any advice for cost-effective fixes?

[Smileybug]

Fluid and filter change on the transmission would be my start. At 100k, it could use it. If that doesn't fix it, you are likely looking at a valve body failure in the transmission. Very common in the VW automatics.

[BB2000]

Is it possible to do the transmission fluid & filter at home? My bf usually does my oil changes and other minor work; being a motorcycle mechanic, he's pretty handy. And is the valve body failure expensive to fix?