I think you're using WAY too thick a string for the install.  When I
was growing up, VW dealers were using nylon twine off of a hardware
type spool to do the install.  For lube, I really like that orange
stuff that they lube the GB folks sell for greasing electrical
household wire through conduit and available at Home Cheapo.  I tie
loops in the ends of the string with solid knots(bowlines) and add
metal rings or larger rope to pull with.  I think the old school VW
mechanics used glycerin for lube, but not sure what's in vogue now.

Long story short..... that 3/16" stuff is WAY too thick and I'm kinda
surprised that you got it in the groove well enough to turn the
gasket lip in the first place. if you are afraid of having the nylon
sting break(it does give a little), find a kite flying guru friend of
yours that has some kevlar kite string.  chances are it won't break
with human strength pulling on it.

Good luck

DM&FS

At 01:21 AM 6/11/2008, Troy wrote:
>I've installed a slider window in a Westy once, and ended up tearing
>a little bit of the gasket, but counted my blessings that's the
>worst that happened. Tried to install another one today, and after
>tearing one corner of the rubber, I gave up in frustration.
>
>So, I'm sure the glass shops all over the world pop these things
>in  15 or 20 minutes, what I'm I doing wrong? I'm thinking of just
>running this over to an automotive windshield repair place at this
>point, what would be a reasonable cost for the service?
>
>Window installation challenged and stained black to the pores...
>
>Troy