MZ 500R rear sprocket needed

Hi, my rear sprocket needs to be replaced this summer but the problem is that I have not been able to find any source where to buy a new one.
My bike is MZ 500R 1992 with Grimeca 16" cast alloy rear wheel. Chain is 520.
Does anybody know who sells these sprockets?
I've looked at JT-sprockets with no luck and German Esjot stopped making them for 500's.
Timo from Finland
My bike is MZ 500R 1992 with Grimeca 16" cast alloy rear wheel. Chain is 520.
Does anybody know who sells these sprockets?
I've looked at JT-sprockets with no luck and German Esjot stopped making them for 500's.
Timo from Finland