George,

 It could be a clearance issue. Especially if the guy rebuilt an engine with a rotor with excessive apex seal clearance. It can be difficult to accurately measure small side clearances. I would suggest if you go to the local machine tool sales place and buy some adjustable parallels or "ball" guages to put in the slot and measure.  The alternative is to check in with your local machinist's QC guy and measure the opening with guage blocks. Using a caliper is always subject to mistakes on the part of the operator! Then use a micrometer on the outside of the seals. When we are talking about a clearance of between .0005-.0015 inches is should be DIFFICULT to get the seals to go in. A clearance that small the seal should have to be aligned perfectly to go in. I bet a lot of the guys don't measure things at all and just toss the new parts in there! BTW I may have a good source for wire edm on the RX-8 rotor seal slot. One of my contracts runs a die making shop where most of their cutting is done in tool steels on the wire EDM.

Bill Jepson