Hi Mario welcome back - I feel (and share!) your pain.
check out
this handy little modification for your secondary adjustment...no more tiny little allen keys.
A few $2 knobs from Jaycar, some new bolts from Bunnings with the ends sanded round (to stop them digging into the secondary holder), and some araldite to permanently unite the above ingredients!
The secondary locking screw is the centre one....Not sure about the primary locking screws...
Adam