Help!!! Thermostat install problem.

[1997reduxe]

Hi all.
Can anyone help me?
I have this mechanic who's installed a new water pump on my 97 Legacy 2.2.
When I drove it home, it leaked around the plastic bowl below it.
He said it seems to be leaking around the bolts, and that the plastic bowl's flange below the thermostat has gotten so thin that the copper bushings in there are hitting before the plastic piece is.
Can you tell me the source of the problem here?
Is he using the wrong gasket, or is he correct in his thinking?
He said that he's ordering a new bowl/housting to install tomorrow.
Thanks for any info.
97