Had some time today so I took the Curve apart and wanted to share the process and what was found.
The first thing was to remove the seat and lid. To do that the cover over the fill and flush button needs to be removed. There is a pin on each side of the cover that holds the seat and lid in place. It is easiest to remove the left (as you sit) side first.
Then remove the pump power unit.
Once the power unit is out you can see two round holes in the pump housing. Insert a round tool through both holes and turn to the right about 1/8 of a turn until the housing releases. I used a phillips screwdriver. The pump assembly can now be lifted out of the unit.
When I got the assembly out I discovered that the hose had come loose from the discharge nozzle.
I fished the hose off the bottom of the unit with a screwdriver and grabbed it with pliers. Then held it in position with a Vise Grip.
When it was out I could see that the hose had split at the pump connection. Apparently Thetford does not use any type of clamp on the hose to pump connection. If they had this problem may have been avoided.
The repair was simple enough. Put the hose back on the pump and secure it with a tie-wrap located above the discharge nozzle barb end. As you can see in the photo this may not be a permanent solution because the split in the end of the hose continues up to the corrugated section. There is also a bulb between the corrugation and the barb caused by the tie-wrap. Am sure that there will be some water bypass in this area but for now that is the best that can be hoped for without replacing the hose.
Reassembly is the reverse of taking it apart. Once the unit was reassembled and filled with water the unit pumped as it should have.