Suesi
look at this switch
Condor MDR1 Compressor Pressure Switch - Next Day from Airlines-Pneumatics

I've had a look at all my compressors and they all have adjustable differentials fitted
but they all british made quality compressors

I really cant see from your photos what they have can you take some in focus?

The top bolt head adjusts the pressure have you increased that?
it may go up to 140 psi safely then your kick in pressure may be raised to keep you over your desired 100 psi

your tank is rated for 150 psi certainly though check on the ratings plate