Arm socket in my rg2570 is loose and rocks in place, its not the washers ive replaced them they are fine. I can see a nut at the back of the bridge that needs to be tightened but its very hard to reach and a socket would not fit in there at all unless i take all the strings off and pull it out.

Any tips of tightening that sucker?

And as well the boss fs5u switch for tap tempo, if i tap a tempo into it but dont turn the delay on, will it have that tap tempo already preset so that it will come on as soon as i hit the delay pedal?
There is a little set screw on the back of it you tighten with an Allen key. You have to just have your bar in and press down to lift the back of the bridge.