Alison,
Are you using good quality collets/collet nut?
You may want to check all your nuts/bolts for tightness...I had X-rails loosen up at about 2 years, and other bolts as well.
When was last time you checked?
I'm a little worried about spindle also....but our 2 Desktops are almost a year older than yours, and with almost religious warm up routines and virtually never doing straight plunges...ours are still humming along nicely(knock on wood).
(Martin...there's been a glitch where the software sets some replies aside for the Moderator to approve for no good reason...and Mod has to go and unlock them....BUT the Mod never even gets notified that the reply is frozen I thought it was fixed) Maybe try again...it was really hit or miss random.
scott P.
2013 Desktop/spindle/VCP 11.5**
Maine