I have an UltraPure ozonator with 5 year old UV lamps (the previous owner of the house said they never replaced them and the pool is 5 years old). They still light up (most of the time, sometimes they don't come on for some reason) but I would like to replace them with fresh ones as I read they become less efficient as they get older. Is this a DIY job? The housing doesn't look particularly easy to get into but I would hate to call someone out to change bulbs!! Advice?