check ebay, they often have top bows & arms for sale
Where were the noises coming from? the back seats, or up in the header where the latching motors are?
My bets are:
1) bad latching motor, and the roof started retracting before it was unlatched
2) Raising/lowering transmisions out of sync, maybe even a broken cable. The roof tends to eat itself if the motors are out of sync.
I went through the whole testing procedure on my dad's 86 cab, and wrote this testing DIY:
http://forums.pelicanparts.com/uploads17/Presentation11273890971.jpg