If tapping on starter fixes the issue, it's got worn out brushes that need replacement. I bought a reman starter for my 2001 and it ran about 50000 miles so I took it apart and put new brushes in and been driving it ever since.
+1 On what @donkpow said, @mcars2020 It's possible this 2nd starter is a poor quality Reman. I was not thrilled with the reman that was installed on my 2001, as it lasted barely 50,000 miles while the factory lasted nearly 150,000 miles!!! I replaced the brushes in it rather than getting another reman, so far so good with the new brushes.
@Theseus161, I can say that Bosch is junk. That's the reman that is currently on my 2001. As I mentioned further up, it only lasted 50,000 miles vs the factory unit lasting nearly 150,000 miles. But in my case I knew what the issue was and knew how to fix it by replacing brushes. If I could do it again, I would have kept the original starter and just replaced the brushes as that was the only issue when it went the first time. But at the time it was our families only vehicle and did not have the time to dig up a place to buy/find brushes.
@Theseus161 I did not make an attempt to buy the brushes from Subaru, I bought them online from a Starter Motor company that sells various brushes for different motors. The brushes/brush holder is 1 entire piece:
Copied from a picture on ebay:
Pulled the unit out and pop the new unit in. I have not replaced that many starters, so I personally have not seen brushless starters, is this something new?
I went to a similar website and bought the brushes to replace my 2nd starter that was a Bosch Reman. But that's good information for others that want to attempt repairing the starter. Had I had the time when the first starter went, I would have done the same thing, but I am now stuck with my Bosch starter, hoping the brushes I put in will last 100,000+ miles.