The KEY thing here is that you should clean off the old grease taking with it the dirt, grit etc - and apply fresh clean grease.
How often - well - if you work on the basis it should never get dry and should be changed when dirty ...... then the answer will depend on your usage and you should be able to judge. I do mine about every 4 or 5 uses - clean off with a tissue and a tiny smear of fresh - and at the end of the cleaning operation before storage.

Last edited by JohnfromUK; 07/31/16 01:49 PM.