Went to fit one today and noticed that there were no middle screw holes to secure the middle yoke (normally use MK where there are 3 rows of screw holes)? Spoke to other guys who said that they either pack the middle row out with washers, or drill a middle set of screw holes. Spoke to Crabtree technical who said to screw the yokes back to the back box. Problem is, if you do that then the switches are to far back from the front plate leaving a gap?