When I go to start my A4, it starts fine 80% of the time. The other 20%, it will do nothing. If I keep turning the key, it will eventually give me a grinding noise, and then start up a time or two after that.

From searching and reading, it seems like this is most likely a bad starter.

a) Does this make sense?

b) Can I replace the starter without pulling the bumper and/or radiator? From the writeups, it looks like I can just pull the a/c belt, a/c compressor, and then the starter, but I've been under there and I know theres not a ton of room. Will I be able to get the a/c compressor out of the way?

Thanks for your help!