The Tiger squeak and other shortages

[Sanjuro]

When the US entered WW2, the USAF planned to cripple German war production by targetting key components- notably, ball-bearing production.
While these attacks were eventually successful (albeit at a horrific cost), many German products were simply built without ball-bearings, accepting the shorter service life this would bring. This in turn explains the characteristic squeak of approaching Tiger tanks in every WW2 movie!
Are there any other components which, while their loss might seem to be a show-stopper, can be done without in the short to medium term?