The bolt that threads into the tab at the top of the smog pump to tighten it down is stripping out the threads in that tab.
It should be easy enough to rethread for a larger bolt, no?
Pull off the air pump hose and try to hold your thumb over the hose. If you can block the flow easily, you probably need to rebuild it, or replace it. There's at least one good rebuild thread on the '40 forum.
If you end up needing a new cat, call Sean at Sunnyoaks Muffler.
sunnyoaks muffler - Google Search
He'll hook you up for only one $. Tell him I sent you.