I've just installed a new window regulator in the left rear door. It went really easy but now I can't get the thing to go up to clamp the glass. What is the probability that the front and rear buttons have both failed? All other wondows work fine.

 

Check the How To write up in the Articles and How To section, make sure you did everything correctly. There is also an articl on how to clean the switches.

 

On my 2007 Scab I've cleaned the switches for the two front door glasses a couple times now since 2009 when I first notice a "hiccup" in operation. The rears .... I opened up & looked at but they were spotless last year as they hardly ever get used.