When I had the windshield replace while in Arizona I learned a couple things.
Yes, originally there are a pair of wires for heating the sealant to aid in removal. Current replacement requirements (US) call for a more modern sealant than was originally used (at least through '86). Apparently the original sealant never actually sets up, which seals very well but may allow the glass to pop out under certain impact conditions. Has to be a real bee-itch in AZ in the summertime, because at 60*F in January this stuff was soft and gooey as bubble gum.
To separate the glass from the car, rather than using the wires, the installer used a stiff hook wire, inserted under the glass and pulled around the opening. This action cut the sealant, allowing the glass to be pushed out a little at a time. The tackiness of the old sealant was such that the weight of the glass caused it to re-adhere, requiring another run around the edge while I assisted by pushing outward.
The new sealant is laid in using a real nifty power caulkgun. Puts out about a 3/4" bead. Takes two tubes of sealant to circle the opening. Prior to laying in the new sealant, all traces of the old stuff has to be removed (time consuming), then the area primed and treated with a rust protectant primer. This stuff went on black, similar to POR15 I think, and had to flash for about 10-15 minutes.
The 126 does not require any clips like the 124 does. The trim clips are riveted to the body and are reused as long as thre trim removal is done carefully. The only items on hand were the two tubes of sealant and a new windshield.
The whole job took about 2 hours start to finish.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.