Recommendations for RWS Diana model 6G rebuild

Umarex should be able to do it also and price would be an important factor 

they are not hard to do but not easy either because there are tricks you need to know and you need more parts then go in the pistol 

the rear cap has 2 parts that need to be the right size, the step spacer for timing and the rear cap spacer so you can get the rear cap screw back in and holds the spacer tightly in place 

and yes they are worth the repair