I use both 1/2 & 1/4" old wood working chisels to clean the surface of the head. A razor blade is usually too sharp and too wide to get in where it needs to go. Don't use the chisels with a hammer or get stoooopid and the head won't be adversley affected at all. Mo MGB used cork gaskets and scraping was SOP.

My SD valve covers leaked no matter how carefully they were installed. I tried several suggestions from this board looking for a sealant. Silicone tends to squish out even when only a little is used. Use too little and it won't seal.

Someone suggested Copper Kote (check the spelling. It's likely wrong.) That works ok even though it says not to use it on rubber gaskets. I had some old school Permatex Hi-Tac on the shelf that hadn't been used in years. I apply to the head and the gasket then let it get a little tacky. No more leaks. Use a rubber mallet to get the cover loose for the next adjustment. Reuse the valve cover gasket multiple times.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.