In the shops I worked in back in the day (mid-70's - 1980s) if we had a Huffy, Murray, etc. that needed new bb bearings or head bearings and the cups fell out (as above) we did the following:
If the cups would fit somewhat tight but still too loose to leave the shop - we cut drink can shims (it was better metal back then) and they were usually the best fix.
If the cups were Really loose, we would take the cup and put the sleeve portion in a vise and slightly deform it (not the race) and then press it back in - voila!
In really bad cases involving third shift bikes, I have even known a frustrated mechanic to slightly deform the bb shell with a hammer...you want yer bike fixed or not?