Hi All, I have a Silavent 354511 model extractor fan fitted in a flat (probably about 15 years old, when flats were orginally built). It's on a pull-cord, and comes on okay, but won't turn off at all when the light is turned off. So, I opened it up, and set the timing mechanism to the minimun of 1 min, and lo and behold it turned off after about a minute. But when I put the cover and casing back on, and screwed it back to the ceiling, it stopped turning itself off at all. I tried this a few times, and each time, I managed to get it to turn off after a minute when it's out of the housing, and hanging loose on the cieling, but everytime I put it all back together, it carrys on running and running. I find this most peculiar. At one time it did run at all, and I messed about with it, and then it came on. I can't replace is easily, as the housing where the fan goes is much larger than the fans which we buy these days from DIY store. The silvent.co.uk web-site no longer lists this model. Any thoughts? Ideas?