You should also check to see if the plastic is broken on the pillar strap - this is the part y'all are talking about loosening and repositioning. I've had to replace two pillar straps because the plastic breaks on the underside and when it breaks the door latch is not rotated far enough to engage the full lock position. Instead, the door latch rotates part way and the door only partially latches. Compare your bad pillar strap to the other doors (esp. the door(s) that's least used) to see if the plastic is broken. M-B later changed from plastic to rubber and this problem went away.

Yep, those allen head screw are really tough to get out even on doors with good seals I've seen bad rust/corrosion that welds these screws tight. I let them soak with penetrating oil for a while like the other members have suggested. Then I use a hammer-type impact wrench to remove the screws (this is the poor man's impact driver that has the appropriate tool attached and then hit it with a hammer to break loose the fastener - my big air compressor is in storage). If you have an air or electric impact gun - then use it because the hammering action greatly helps to loosen these screws and avoid damaging the allen head portion of the screw. If you should round off the allen head screw then I've used a small sharp chisel to cut a groove in the screw head, then place the chisel in the groove facing in the direction to loosen the screw, and then strike it with a hammer to loosen the screw (this may take several tries speaking from experience). If this fails then you made need to drill through the head of the screw and then use an easy out.

Good Luck!
Tom

__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.