I have a small oil leak coming from the back of my spin on oil filter adapter. The adapter I have looks like a plate with eight holes in a circle and a coupler through it that then has a 30mm(ish) nut put on the coupler to secure the plate. The plate appears to be able to be taken off without removing the coupler from the bike but it's stuck on there. I tried a dead blow hammer and putting allen wrenches in two of the eight or so holes and spinning the whole thing with those and a long screwdriver but didn't have any luck. Is there a good way to remove these plates?