how to stop a leak from a SIME super 90 boiler?

i've taken the front cover off, and cannot see anything major leaking, or come undone. however, from underneath i can see drips eminating from the blueish grey metal plate that surrounds all the main in and out pipes into the boiler.
I cannot see into it very well though as I can't remove the plate, or indeed the front plate which houses the dials.
any ideas how to remove the plates, where the leak might be coming from, and just how to fix it, or how much i should fork out on a plumber?