I've noticed that when I slowly press the sustain pedal, the dampers don't all raise at the same time. Also, then I release the pedal, some dampers touch the strings before others. This is causing some notes to buzz a bit. Is this an easy adjustment I can make myself, or should I just call my tech?
It is an easy adjustment for a novice to make. The difficulty is doing it without doing more damage than a tech's visit would have cost. I see far more DIY damage than improvement, so I see the odds of you getting what you want by doing it yourself as a first timer as slim. I speak for many techs when I say that " if you must go for it, be cheerful when you get our bill to repair it." So, here's one way
Do a closer check of your dampers. It isn't enough to say they don't lift together. Does one end lift before the other? Or perhaps, the middle rises first? Or, is more a scattershot result? Lift them all up with the pedal, then play a full bottom to top, two finger(get the sharps in there), glissando as hard as your fingernails will bear. Immediately begin lowering the dampers onto the strings, paying attention to the progression. Going slowly will allow you to pin point the last remaining string to be sounding. It will tell you if the dampers are mostly together with a few early and late ones, or if they are all over the place. This is the reverse of watching them lift and can tell more about how things are working vs appearing. Notice that some dampers begin moving while still damping (trichords), while others free the string at first lift,(blocks).
Going slowly enough , you may be able to detect which ones sing on landing. You can roughen the felt with a small strip of 320 silicon/oxide paper. I have had this problem in the recording arena, here. Close mics pick that yawp up. The abrasion therapy isn't a long term solution, but will buy maybe a year or two for a home piano. A flexible strip about 1" wide and 10" long will do it. You may want to check out the price of having some dampers replaced before getting too aggressive with the sandpaper.....
The above is all DIY guidance, woefully lacking in caveats, detail, and responsibility. Anyone with a RX6 that is having damper problems really should call their tech.