Yes, you can carefully slip the cover back onto the regulator in between adjustments, but be very careful not to short anything out. That cover can definitely make lightning strike if you touch the wrong spot. The center point set is the current regulator, which prevents the generator from overloading itself when recharging a very low battery. It's usually set to 30-35 AMPS, (not volts) by leaving the headlights on for an hour or so, then quickly checking the current output at fast idle immediately after startup. It's also possible to use a carbon pile load tester to put a heavy load on the battery and adjust the current control with the load applied and the engine revved up.
Jerry
