Yes you can do it yourself. Google for "Disassembly Canon 50mm f1.2" There is a very good page out there describing exactly how to disassemble and clean this lens. It is quite straightforward. It does require a lens spanner but you may be able to extemporize with a pair of circlip pliers, a metal workers compass (ground and adapted as required) or similar (or just buy a pair on ebay - they are cheap) If you cannot find the relevant page, private message me providing your email and I will email you the page to you as a HTML file - I have it saved offline on my PC for ready reference but the primary internet site my copy was downloaded from seems to be down. The author of the page is named Johan Niels Kuiper so try including that in any search.