depth change on 3d????

Tom, Is it possible that a 3d detector that once could air test at 11 or so inches drop to 8 or 9 inches over a few years ????(2004-1021 las banyos model) dj

Hmmmmmmmmm=

Very doubtful...... yet possible.
Do you have a different coil (same size) that you can test it with? Maybe a buddy's coil? Or a local club?

Never heard of this happening but with electronics and age imagine it could. Like Tom's idea of trying a different coil as coil problems can cause many problems with any detector and certainly a good starting point...

Weak battery?