I had some seat work done by my neighbor who is in the furniture repair business. He dyed and touched up the seats but said he couldn't repair where there is stitching already because the extra holes from the needle will weaken the leather and they will rip and be completely useless after that. He said to wait until they are shot, then he will replace the covers. If there is stitching there, you can't stitch it again or it will continue to rip. Has it been stitched over stitching? I am sure there are replacement covers as I have seen them advertised. Let me know if you need this information. Good Luck.
'85 500SL (Euro)