The right flippers at times get stuck during game play. I have rebuilt them and I also changed the 1n4004 diode. Turning the power off the flipper returns to it's normal position.
Following the below guide and I still have the same problem. Anyone have any ideas that I could try?

From Clay's Repair guide

Flipper Gets Stuck in the Up Position...
Before proceeding with repair, first determine if the stuck flipper is a mechanical or
electrical problem. If the flipper is stuck in the "up" position, turn the game off. Does
the flipper return to its normal "down" position? If so, the problem is electrical.
Otherwise if the flipper stays up even when the game is turned off, then the problem
is mechanical.
Electrical: On Deger (Playboy, Monday Night Football) and solid state flipper
games (Robocop and later), check/replace the flipper coil diode. If the flipper
coil diode is broken or shorted on, the flipper coil will stay energized after first
using the flipper(s). Replace this diode with a new 1N4004 or 1N4007 diode.
The counter EMF (Electro-Motive Force) produced by the magnetic field in the
coil collapsing is a reverse polarity voltage. This reverse polarity voltage can
also cause damage to the solidstate flipper board.
If the solidstate flipper(s) are still stuck in the Up position, then check the
solidstate flipper board's TIP36 and TIP32 transistors. The TIP36 transistors
supply the initial power voltage to the flipper coils, and can be easily
damaged. The TIP32 transistors supply the "hold" voltage to the flipper coils
(and hence are not as easily damaged as the TIP36 transistors). Both TIP
transistor types are easily checked with a DMM, see the transistor section for
more details). If a TIP36 has failed, it will usually hold the flipper "up" as soon
as a game is started (or sooner!) If the flippers are still stuck in the up
position, but only after the flipper button is initially pressed, check the S2800B
Silicon Controlled Rectifiers. Often the SCRs will "gate" in the holding voltage
circuit, causing the flipper to remain energized as if the player was holding the
cabinet flipper button in. This was mentioned in service bulletin number 58.

I have before but I when ahead and did it again just to be on the safe side.
The flipper won't stick every time