Hi,
First question is very important: Is there any leakage around the Hexagon Socket Head Bolt on the bottom of the fork? If so follow step 1). If not follow step 2).
1) take fork assembly off, turn upside down, manually compress, remove Hex bolt on bottom, clean, apply locking agent like Loc-Tite or fingernail polish and reinstall bolt. The washer is made of copper and is a one-time deal but, I have reused them many times with great success as long as you use a locking agent.
2) There are two problems that come to mind. One I am positive about and the other is probable. 1st> The is not enough fork oil in each tube. That will fix a lot. It will get stiffer, prevent bottoming as much, it will also help the knock ( I am guessing that it knocks when it rebounds - coming up) 2nd> Spend a little time bleeding the forks without the spring in. This will also help. Although, they will eventually bleed themselves out.
Hope this helps,
Mike.