otherwise you can get silicon lubricant spray ( which is prolly the spray form of what you've got ), and spray it into the channels.
With your "goop"
, I'd put on gloves, and put a bit as far down the channels as you can ( with the windows down ), and then wind em up a down a bit . . . I'd also aim only for the vertical sections of channels, since they will not spread the goop onto areas you might touch while using the car / windows normally . .
I think you've prolly gone the expensive route, but no doubt it will fix it ( barring a mechanical fault as per dellboy's suggestion ). Let us know how it goes - maybe it is worth the $45 (but I doubt it!)
Oh, as for the health warning - the spray silicon stuff also warns of this - apparently you can get silicosis ( which is nasty ), if you get too much into you )