I bought one of the Lee-Valley low angle block planes a year or so back. In general, I'm very happy with it but lately I've started to have an interesting problem with it.
I generally keep it set for a very small cut, with the blade just barely sticking out and the mouth closed down to a sliver. What I've started noticing lately is that after I've used it for a while, the mouth tends to close down until there's no slot left at all (at which point it stops cutting). I tighten up the mouth adjuster knob as tight as I can (by hand), but it keeps slipping closed slowly.
Anybody seen this before?