Many thanks guys. I took it to the beach this past week and got another 3-4 hours run time on it. I am still happy with how it is running but do have one observation. Because of its size and the sheer mass or aluminum in the displacer and power cylinders as well as the piece they both connect to, it takes more time for it to heat up to running temperature, especially if indoors with the AC running. Those familiar with this design will note that I did not add the fan between the two cylinders. This can still be added later but with sustained runs of 40-50 minutes it doesn't really seem to be needed.
Bill