Hi everyone, hope someone can help me. I have a 1998 an250 Burg which, for its age, appears to be in cracking condition with only 5100 miles on the clock. However, the riders back rest (which on this model appears to be non-adjustable) is, quite frankly, a pain in the a**. I want to remove it to install a gel pad and memory foam insert in the main seat but, try as I may, the 3 domed nuts underneath the seat (which appear to secure the back rest) just keep turning without loosening or, indeed, tightening. Am I missing something?