Pool Fountain Half power

I have a brand new fiberglass pool with a fountain.  We have a 1 1/2hp pump. We have a built in fountain that waterfalls into the pool from the side with a diverter on the pump side to turn the  founatin on or off.

I have noticed the last few days that half of the water fall is not as strong flowing as the other half. It is a plastic 24" waterfall that they had to hook up to the pvc piping.  I think they had to use some heat to bend it to connect. Im worried about a leak, but the entire covering is stone and dont want to tear it up just to check.

Ive used a ruler to try to clean out any blockages and it persists.  If I turn the fountain on full, both sides are fine and the pressure sends the water to the middle of the pool, but when we kick it back to a waterfall it wil, after a short time, go back to one side is not as strong as the other.  There is only one connector and one pvc pipe that it connects to.  I used the description “sides” but it is only one piece, and water is pumped thru the middle.  any ideas would be greatly appreciated.