Kizer Mini Sheep Dog stiff liner lock?

[Armen]

Is this by design or did I end up with a defect? I tried washing the knife with warm water and soap and completely drying it out, tried loosening the pivot, tried #2 pencil on the tang where the lock engages and nothing helped. On top of that the liner lock is really thin, recessed and there is no cutout in the scale to get to it easier. takes the fun out of flipping when your thumb gets sore from disengaging the lock.

I really like the knife a lot so looking for some feedback.

FYI, the newer ones come with 154CM steel and not VG10.

thanks!

Armen