My 2188 did the same thing. Heres what I did.

There is a hex plug on the back side of the aneroid body. Take it out and you will see a star wheel shaped adjuster similar to a brake adjuster. Screw this wheel all the way down, or until there is slack in the spring.

Next replace the supply pump. An easy change and about 120.00$$

Brought mine to life without turning the pump up.

Have a good day,

John