Pneumatic Hammer Drill

[philtivvy]

Hi
I have several cheap Chinese made hammer drills which all suffer the same problem. The hammer action has gone from very strong to negligible.
I have replaced the 'O' rings on the piston and on the hammer that slides between the piston and the end of the drill but this does not seem to improve things.
I have tried the old 'O' rings lubricated with grease and with all traces of grease wiped off, similarly the new ones. Again no improvement.
I have carefully inspected all the components for wear and/or scoring and found none.
Can anyone advise me how to overcome this problem?
regards
phil

 

[DiyEx]

As a fellow Devonian, i'd love to be able to offer you some sage advice on fixing this problem. Sadly, as you seem to have covered all the bases in regards to finding the fault, the only advice I can offer is: Don't buy cheap Chinese drills...

(i'm guessing Tiverton from your username?)