beru distributor cap fails
 

got a cap from vertex (beru) cause it was a couple $ cheaper.
It lasted all of 100 miles. the carbon tip came loose from the spring. There's a center burn mark also that could have been the cause or the result of the tip comming off
I guess long story short, get the bosch.

they tend to fall out un-noticed as the cap is turned over to install it. once in place, if it stayed in there, the rotor would keep it from going anywhere.