Shorter Rebound Knob for Marz 66?

I put a 2010 Marz 66 RC3 Ti on my 2008 Nomad, and I took it out for its first ride today.

The red rebound knob is hitting the bottom of my downtube So I'm looking for a shorter rebound knob to clear the downtube. Does such a part exist?

If not, I guess I"ll pick up a new rebound knob as a backup, and take the grinder to it