I have a TRX 2.5 in an older Nitro Rustler. I'm trying to disassemble the top half of the cooling head so I can get at the piston and make sure it's clean inside. However, the 5 screws holding it down are just completely jammed, and I can't even get it to budge the tiniest bit. I have the correct allen wrench size, cause it's providing me with the resistance, but I just can't loosen it at all. Any tricks that could get it loosened up - sprayed some Liquid Wrench on the sides,but nothing yet.