bravo that i bought has been stood for a wee while, and the windows are sticking, but they do work. how do i loosen them up a bit?
DO NOT use any oil based lubricants such as wd40 becasue that will make them worse in the long run.
the thing i never understood about greasing the centre runner is that only a very small amount of the overall friction will come form the centre runner. it is far more likely to be excess friction where the glass rubs against the window seal and side runners that causes the problem. if you try pushing a window up by hand with the centre runner disconnected its still vary hard. if you look at how the centre runner is built you can see there is only a very small area of contact so even if no grease was used at all it should not cause a problem.