Over the years I have had various makes of Stanley Type knives and
none of them have really satisfied me .. My most recent one is an
Irwin which folds open and has a magnetic blade recess. Using it a
couple of days ago to cut plasterboard the blade was getting pulled
out of its recess so it would seem that it isn't being held closed as
tightly as when it was new .

Is there any make that will grip the blade firmly? ...maybe they
should make the blades with a hole in them so they can be held by a
screw ?

Any recommendations welcome.