When I recently changed my fork seals I was able to luck out and use the my hydraulic jack handle to hold the fork damper rod while removing the lower allen bolt.
Today I had no such luck when changing the fork seals on my SecaII. In order to hold the fork damper, I welded up a tool. I used a metric bolt & some small round pipe to make a holder. The nut size is different on the Bandit 400, but the same type of tool should work for it too.
If anyone is interested in a similar tool for their Bandit(s), I'd be willing to build them one for the cost of the materials (~$6). Someone will have to let me know the size of the nut/bolt to use as I don't really feel like pulling my forks apart again to find out. I believe it's in the neigboorhood of 27-30mm?
Here are a couple of pics (I know, I know.. I welded this up VERY quickly):
remember,I built this tool for my SecaII so the bolt/nut on the end is smaller than that which would be used for a BanditoI've also thought about making it "universal": Using a threaded end so you can use any size nut you want and using a setscrew or cotter pin to keep it from turning.