2001 Town & Country LTD window regulator

I just finished replacing the second power window regulator in the
past 2 weeks on this vehicle with only 90,00 km on it. These
regulators must be pieces of crap for they were rarely used maybe 5 to
10 times a month. They were stamped made by Meritor LVS from
Gordonsville USA. Don't know if they were original equipment. Could
not see what was wrong with them but they would go intermittent and if
you banged on the electric motor housing they would work. The brushes
were good and I even replaced a set to see if that would help but it
did not. Anyway the question I have is I noticed that when I moved
the windows up and down in there tracks without the regulators hooked
up there was some very slight stiffness or resistance on the way up
but they fell nice and smoothly on the way down. Seems to be related
to the rubber felt portion that the window rides on. I was wondering
if there was anything I could put in these tracks like maybe talcum
powder or some other product that would make the window ride up a
little smoother. You can hear the regualtor motors working a little
harder on the way up now and I thought maybe something could help to
make them last longer.