Hi SvenDriver
Had the same problem, which I solved last year with a strip and paint. The A frame, dedion tube, radius arms, and roll bar all went back to Arch to be re-powder coated. The chassis was stripped, and painted using black enamel. It all looks like new, and cost less than £100 .
I don't recommend hammerite, because it has a very soft finish.
Chris....
H15 SVN Get it !