Front glas cracked -> proximity sensor broken topic

My i9305 dropped and now the front glas is cracked. screen & touch are still working, but the glas in front of the proximity sensor is cracked.
it does now always report 0 (attached to ear). Only with bright light in a specific angle I can trigger the proximity sensor, so I know the sensor itself is not broken. So the screen stays black when calling someone.
I tried recalibration: http://forum.xda-developers.com/show....php?t=2353972
but it did not change anything.

I dont want to replace the front glass, because I heared it might cause more trouble (with screen, touch and the sensors) - besides the proximity sensor everything does still work fine.