Check it for normal wear and tear first.

LTG : )

An easy fix - loosen the spring.

I had amazing success with a similar problem on the insanity falls shot with the upper flipper on Wh2o.

The most minor change in tension made a huge difference in flipper strength.

Not sure if it also applies to the upper playfield flipper that loads the couch, but I know that the long shaft of the upper playfield flipper that loads the TV sometimes binds on the edge of the upper playfield.

Loosen off slightly the black knurled knobs that hold the upper playfield in place and see if that makes any difference to the strength of the couch flipper.

Do you have the flipper strength set to high? Try that and see if the ball makes it up easier. It worked for me.

Yes. That is the one.

Just manually stretch it so it's not as tight, but still retains some tension. But be careful not to overstretch it removing all tension. If that happens, the spring won't work at all. Best to just stretch it a little bit at a time to measure the improvement.

The spring does not need to be wound really tight to snap back effectively. An overly tight spring can weaken the strength of the flipper. A slightly looser spring will still snap back fast enough, as long as the spring still has enough tension to return the flipper to the resting position.