You can organise replacement pots from Thrustmaster. If you are out of warranty they will charge you a small cost for the part and shipping. I just got an antenna pot for less than $10 for example.
See the instructions on the bottom of this page:
http://www.vaaf.net/wiki2/index.php5?title=CougarFailing that Red Dog over at the Viperpits.org forums used to sell pre-wired throttle pots matching the originals.
On replacing the pots altogether the solution for that is CubPilots HS1 Hall Sensor Throttle Kit at:
http://cubpilotshangar.net/page48.htmlCubPilot can take some time to respond to emails.