Good question, without replacing it to try a new one you won't know. Do you have a friend you could borrow a throttle from?  One extra problem mine had was that I couldn't get it into 'manual neutral' (to rev it out of gear) I never had used this feature but once it started playing up I found out it didn't work. The reason I mention it is because once I pulled my old throttle apart, I think it could be related.  What's your location?