He should make sure that he is using the right lugs for the correct rim. I had a 1996 Mercedes with mag wheels. The spare tire was mounted on a regular steel rim, and if you tried to mount the spare with the mag lugs, they were too long and would not bottom out. Mercedes provided the lugs for the spare steel rim which were a tad shorter than the regular lugs.Strange- if the lugs were properly torqued down the lugs should not loosen. I'd look closely before dismissing it as fixed.