There is an adjustment procedure to make sure the roof is seated properly. Should be 1mm lower than roof line on front end, and 1mm higher than roofline on rear of roof. If he has access to MB repair DVD there are videos showing the adjustment. Hope this helps.

__________________
Dennis
2006 E320 CDI Black/Black Leather. Nav, HTD Seats HK stereo 32000 miles.
2000 VW Passat 1.8t 300,000 miles as of Dec 09, 2009 original owner
1997 E300d Silver 300,000 miles As of Jan 05, 2010
3rd owner SOLD