Pull out your ext valves and check the pistons for scuff marks on it there should be none while you have the valve clean them up and check them out for rusted or Brocken springs.
So I put a set of bikeman heads and pipe on my sled last fall but now I can't get it to build any rpm 7300 to 7700 on my 800. seller said they are 13 :1 head but it lost a lot of snap in the sound of motor thinking they are low compression heads is there any why to tell
With out tearing it apart...
sorry to hear your dad is having troubles getting it up but you can try moving where you front track shock mounts on the top. this lays the shock down a bit and helps to soften the skid a bit.