I just ordered a new MD and told my 9 year old that he could use my old one when I get it. The old one (silver sabre) has been leaning in the corner of the garage for about 9 years. I bought it about 18 years ago and never spent enough time to learn how to use it. The MD I just ordered (Ace 250) will be my 2nd, but since 18 years of collecting dust doesn't count as experience, I consider myself a newbie. Anyway I took the old batteries out (yes they were in about 8 years),and put in new. They hadn't really leaked much, but now there is just a loud constant tone when I turn it on. I was really hoping to let my son play with this one so we could detect together. Anyone have any ideas for a possible fix? One thing I thought of as I was typing is, I do a lot of woodworking and it may be full of sawdust. Will these things hold up to being blown out with a compressor? Thanks in advance for any help.