Carburettor bolts to crankcase

Hi whilst fitting a new carburettor to px 200 disc (malossi 210) found threads had gone on the case (on the hole closest to rear shock)and bolt wont tighten which now i think needs a helical thread fitting.The real problem ive got is that aer this happened i stupidly ran the bolt down the threads with carburettor off to see if they would clean up the dissaster happened it puncured a small hole through casing into casing .

Any ideas on how to rectify this small hole its about 0.5 mm and is in the part that looks ground away???



screw the bolt out and use a thread sealer like this, than it works: