Been "needing" one of these original Rider Ericsson engines here for years now, but they appear to be somewhat scarce, as they very rarely show on Ebay.
However, Lady Luck was finally on my side, and i managed to bag a nice example a couple of weeks ago.
It could use a bit of attention, with some shims inserted on the various linkages, as they all appear to have quite a bit of sideways play, but given its fantastic cosmetic condition, and extraordinairy eager to run, i am overall very very happy with this addition.
A little unedited movie here, of the initial testrun "straight from the box":