The unit itself can be removed easily. Disconnect the drain line, then rotate the the locking ring on the unit and it will just drop right off. Just be ready to accept the weight when the ring releases.

Slightly more aggravating is removing the drain fitting and replacing with a new one. However, if you've done even simple plumbing work before, I have little doubt that part will make easy sense to you.

Thanks! I'll give it a try this weekend.
Carolyn