I too bought my parts from the same supplier, Germany, whole kit belt/waterpump etc. I also bought the Aux belts. I am an engineer and wanted to understand exactly what was happening with the pins/cams so did some measuring to reassure myself. I first rotated the engine until the holes in the cams were visible. I could see and feel a slight step indicating the holes were not EXACTLY in line. I removed the circlip from the pin and removed it from the part that screws into the cam cover (the collar), this allowed me to see/feel clearly what was happening. With slight rocking I got the pins to drop into the holes. I measured the height of the pins once dropped into the holes and then again when resting on the cam. I then slipped the collars that screw into the cam covers back over the pins and screwed them into place. The circlips do not rest on top of the collars when the pins are full engaged, a gap underneath, which confirms what you described. However, by doing these measurements, I was able to satisfy myself that when I could see the pins resting at the correct height all was well. When I slipped the collars back over the pins and screwed them into place, they were fairly tight, not so much that they needed force to screw in, just a little more than finger pressure. I came to the conclusion that if the pin/collar assembly is fitted as one, that is screwing the collar in place and engaging the pin to the cam at the same time, it could be more difficult. I also came to the conclusion that as the pins were a close fit in both the cam cover and the hole in the cam, the screw-in collars were in fact unnecessary, I could feel the pins engage, drop the correct amount and lock with no movement. With the cams in the correct position and the pins dropped into place, I then removed the pins and offered up a 9mm pin to the holes. The pins dropped into place with an obvious loose feel, allowing me to rock them. As you can imagine, if the 10mm pins slid into place then there would obviously be some play when using a 9mm pin in their place. I thought I would pass this on because it might help others who decide to do the job and are a little confused by differing feed back. In summary it appears to me that is very unlikely that these engines differ, particularly as the part numbers for the Fiat tools remain the same. However, the genuine tools may be manufactured to higher specifications and subsequently fit as intended. The various aftermarket tools are probably of lower quality, and bearing in mind the accuracy required for alignment, are a poor fit. This would explain why some people have found that reducing the pin size simply by polishing has helped, whereas others have needed to reduce the pin size by a greater amount in a lathe.
