The bobbin cover design made sense to someone I guess. But for the life of me I still am amazed at the number of machines, Singers and others, that are missing the bobbin covers. Especially those I've watched on GW.
If it's a 66 the only thing that could be missing from the back would be the inspection cover.
As for your comment about "sweat equity" I love doing that. When I'm done I can look at the machine and say: "I did that."
Joe