The cover tends to warp over time and if a new gasket is installed dry, it will probably leak. Once the cover is off and cleaned up, lay a straight edge along both sides. Any warping will be obvious. The cover can be pressed back to straight but it is brittle and may crack. Lapping with some 220 wet n dry is another option to true it up. A light coating of gasket compound will help prevent any leaks. Don’t forget to pick up a new 310058 (18-0182) seal for the t-stat as they don’t come with one.
