THE 124 SUNROOF MECHANISMIS SIMILAR TO THE ONE ONE MY 201 CHASSIS. IN FACT,I USED A 124 SHOP MANUAL TO GRT HELPON HOW TO FIX MINE. MINE WAS DOING THE SAME THINE WOULD OPEN AND WOULDN'T CLOSE ALL THE WAY.
I POOPED THE SUN ROOF INTERIOR PANEL ( IT COMES OFF LIKE A DOOR PANEL) AND IT EXPOSES THE SUN ROOF SLIDING MECHANISM, A SINGLE CABLE HELD IN PLACE BY TWO SCREWS. MY SCREWS FELL OUT. I PUT IN TWO NEW WITH LOCTITE AND ITS BEEN SUN IN THE SUN. WORKS PERFECTLY.