Bob, Really not familiar with the Highland E4, but with mine (Barranca Cab Combo) the gasket does lay totally flat on the top of the tank. The u-shape you refer to is filled in with a thick felt piece cut out to the shape of the opening with a hole for the shaft to run through, thus preventing any oil from flying out. The u-shape opening is grooved to allow the felt piece to sit in it to help stop the oil. Maybe this is how yours is and maybe it isn't. Like I said I'm not familiar with the Highland E4. Hope you find your answer.

From Ward - February 08, 2010 at 22:36:25

Message: 68751