starter Problem - 2001 Toyota Corolla. Should this be easy to change or should I refer to a mechanic? Battery is fine, it chatters when I try to start the car.

The starter chatter could mean a new starter is needed, but just to be sure, make sure the terminals on the battery are good and clean, and securely tightened. Sometimes the terminals will come loose and cause all sorts of problems with vehicles.

If they are then unfortunately as you said, a new starter is needed... however replacement of the starter isn't very fun on the 2001 Corolla, if you've not worked on many vehicles I would suggest to take it to a shop to get it done.

But if you feel up to testing your patience and your knuckles in some spots, if you follow the manual you could more in likely manage it, just not a very fun job at all.