Received the boat and motor as a trade. Wanted to change the gearcase lubricant oil in the lower unit but I could not get the upper vent plug screw to unscrew with a normal flat blade screwdriver. I can get the lower screw off. I was told by the dealer I got the boat from that a special tool is needed to remove the upper vent screw plug, called a t-bar. Has anyone heard of this and if so where can I get one?