My prints for the new upper corners are done.

When I said the top corners were securely glued on, I wasn't joking.  Two drops of super glue per joint, and spin the rod before it sets.  I know this stuff works great on ABS, but the whatever the fiberglass rods are made of must react similarly cause this stuff is permanent.

Tried to remove them by hand.  That was a kinda funny and made me feel bad.

(miss) Used an angle grinder to try to weaken them.

More demoralizing dancing with a seemingly indestructible triangle ensued. 

Finally a channel locks and a meat cleaver were enlisted.

Well at least I don't need to worry about them coming apart.