Hi Mark
The front panels are held on by those countersunk, black hex headed machine screws visible on the back of your instrument. If you have a front panel that's come loose you can tighten them up from the rear. We do this with a precision torque driver set to 45 cN.M (45 Newton Centimetres) +- 1cN.M. We use precision drivers with a range from 20-120 cN.M here, and that specific torque was tested to show good vibration resistance without over straining the mating thread (which could strip is overtightened) or instrument structure, which could be distorted by too high a value.
You would be best off to beg steal or borrow a torque driver from somewhere if you could (and I'd probably re torque all the screws while I were at it). In a pinch you could just tighten the screw down by hand. I'd be fairly comfortable doing this as I have a pretty good feel for what 45 cN/M feels like, it's just a nice sort of tightness, and the value is probably not desperately critical, but that's your call really. If you'd like us to do this for you and you are happy to cover shipping costs, we'd of course do it at no charge here, but that seems overkill.
If the screw does come loose again, I'd suggest using a drop of Loctite anerobic thread lock on it, the next time you tighten it. Link to product on RS here. This usually works wonders for threads that routinely loosen from vibration, and there is nothing in the engineering to stop you using it. You can probably get this locally at any good engineering supplier. At a pinch I have found that some clear nail varnish diluted with a little acetone works ok too, though it's a rather low tech solution with possibly variable results. Don't use glue of any kind that's not formulated for thread locking, you may never be able to get it apart again.
I hope that helps and I'm sorry the panel has come loose in the first place, that shouldn't happen. Apologies for the delay in response, we've been really busy here with the new Tau build.
John