I am sceptical. In my experience, the three main faults on Umarex pellet firers are (a) worn, broken or otherwise malfunctioning pawl; (b) broken trigger bar; (c) seals. Only seals are an easy fix.
And on the 1911 only, grip safety issues, given that they took John Browning's excellent firearm grip safety design and made it into a CO2 pistol design nightmare.
Failure fully to index the cylinder can also be a cylinder fault, perhaps that the teeth that engage the pawl are worn. There are definitely at least two types of cylinder "magazine", with different bigger teeth, which suggests an upgrade at some point to minimise malfunctions. But the mags with a P30, as a comparatively recent product, should be of the later and presumably improved type.