I own a beautiful no.7 plane made by juuma : it’s a copy of Lie Nielsen , that is a copy of Stanley bed rock pattern. It has a very good steel blade and comes from the factory almost square and flat: i need only 20 sweeps on 180 grit sandpaper to get it flat. The problem is..in the frog. i notice one screw, the left one slightly becomes less tight after few minutes of work and plane position changes in left 7 right axis…what could i do?
My old mechanic teacher adviced us to use laquer for finger nails to lock bolts and/or nuts. Its dirt cheap, holds relatively well on most stuff, and comes off without too much trouble (acetone/nail laquer remover).
It’s less strong than lock fluids though, and likely to ruin paint/finishes.
If its a relatively new plane, I would ask the seller if he could fix it or replace it. Restoring old tools gives me a good feeling, but repairing new stuff with production faults just don’t get me there.