Before you go nuts with heavier springs, first completely clean out the interior of your bolt body. If you've soaked it in MEK, carb cleaner, brake cleaner, mineral spirits or Milk of Magnesia, chances are it still has an interior coat of varnished cosmoline.
Completely disassemble your bolt, and scrub the interior with successively smaller diameter bronze brushes dipped in MEK, carb cleaner or even Citri-Strip paint stripper. Once you think it's clean, scrub it out again.
After reassembly, if ammo that works OK in other rifles, still won't fire in this one, consider a new 22# Wolff spring from www.gunsprings.com
Remember that the heavier the striker spring installed, the heavier the trigger pull will become. 22# has worked in every one of the Mausers I have that required a heavier spring.