For anyone experiencing a power supply failure in their Pegasus - as I did in my Pegasus32 R4 - after a lot of looking I was able to find yesterday a replacement via eBay from KDM Power in Houston. The unit arived today, install took 10 minutes, and my system is up and running again. 

Here is a link to the unit; I found the people at KDM to be very knowledgable, responsive, and helpful:

https://www.ebay.com/itm/336158204663

I have no relationship with KDM aside from being a happy, and relieved, customer.