Please also check previous posts, using the search function. I recall Joe Alexander mentioning that sometimes one or more nuts can come loose, causing some operating problems.
In case of major trouble - I believe you can find rebuilt units for around $1,500-$2,000. Used ones should be no more than a few hundred $ although for all the work that's involved I would go with a rebuilt one rather than taking a gamble, unless you have a lot of spare time on your hands.
Cees Klumper in Amsterdam
'69 white 280 SL automatic