Loose front standard on GX680

Anyone know how to tighten it? I've tried gently prying the knobs off (thinking there might be screws under them) but they don't want to budge and I'm afraid to bring my usual style of percussive maintenance into play.

It's not such a big deal with shorter lenses, but with the 210mm the front sags down considerably, usually after I have the shot perfectly focused and have just started to depress the shutter release. This has lead to some interestingly focused shots. Sometimes interesting is nice. Sometimes.

Eh, maybe an insult but have you tried the little screw under the front standard. If that is loose the front standard drops (guess you have done that already, but I personally have forgotton it on occasion and it needs to be tight!).

Greetings, Ed