I purchased the complete new manifold rather than guessing which or how many valves were leaking. The repair wasn't too difficult,but I spent a lot of time cleaning the cook top parts before reassembly. Remove the knobs, remove 6 black screws, remove cover over manifold. Remove 4 screws and a bracket, remove burner caps and 10 torx head screws and the burner hobs. 2 more screws in the front of the cook top. 4 that hold the manifold to the top and it's apart. I used flare nut wrenches to remove the gas lines from the manifold. The new part fit perfectly and now my range no longer has a propane smell every time I walk by it.
I probably could have replaced the manifold with out taking the entire top off, but it really needed the cleaning. Not a hard job, just time consuming.