let me see now.....
An O-320 with low oil pressure, high temp, reduced power output; landed it before it quit
an O-360 with a mag drive failure yes I know you can select the non failed mag but on take-off that is a little tricky
an O-320 but could have been anything, the throttle cable stuck solid
an O-200 with two plugs out on the same pot
another one on an O-360
Cracked cylinders on glider tugs, various
a volkswagen in a falke with a both mags dying progressively, and simultaneously
don't ask about cars......I drive old cheap ones
I actually managed to nurse them all onto airfields except for the cars.
They don't have to be complicated to fail