In order to cut down on the amount of threads being made on certain controllers for anyone who has problems with them; post your problems in this thread. I'll start. I have a Piranha Pad PS1 Controller by Interact that has the X, Triangle, Square, and Circle buttons that don't work. All the other buttons work, though.
I think we're better off having a thread for each controller instead of one thread for all of 'em.
If I were to try fixing your pad, I'd open it up and have a look inside. Does it have a single ground for all three of the dead buttons? If so, start looking for broken traces, cracked solder joints, etc. If it has a separate ground and return for each button you may be SOL. Trace the circuit and see where it goes. Post pics if you can get make a clear image of the PCB.
Also for D-pads in general, sometimes the switches or contacts go on their own tiny sub-board separate from the rest of the PCB. A poor design would allow the wrong buttons to be under the wrong directions via rotation. This happens a lot with the encoder wiring in dance pads too.