Canon U.K. have just told me in writing that they can’t repair my 300mm F4 lens as they only keep spare parts for 5-7 years on all their products. I bought it new in 2004 for £1000. I am not certain what part is required, but suspect the image stabilizer module. What a terrible service. I have always advised people to buy second hand gear as most photography equipment is under used. No longer is this a good idea. The second hand value of Canon gear is now much lower. It is a pity there are only two dominate players in the camera manufacturing market, Canon and Nikon. It needs more competition to drive better customer service.
One of my arguments for selling my 600mm F4 IS lens last year was that it was 10 years old and if anything went wrong with it spares would not be available. My 800mm is okay for another 4 years, then £8000 could be worthless!