liftgate difficult to unlock

I am the original owner of a 2006 Gen 2 Prius with 43,000 miles. I used to be able to unlock the liftgate easily by pressing the appropriate part of the liftgate. But recently, it's become very difficult, almost impossible at times, no matter how hard I press. I eventually succeed, but it's no fun. Pressing the unlock button on the driver's door or the unlock button on my fob doesn't help. And my wife can never open that liftgate.

I think it's unrelated, but I should mention that I put some duct tape on the rubber of the spot I press because the rubber was beginning to disintegrate and leave black rubber "soot" on my fingers. Has anyone else had my problem? Any solution I can try? The car runs fine. I am proud to say that despite not being too mechanically inclined, I did successfully replace the auxiliary 12v battery last year with an elearnaid yellow top. I have been thinking about trading in the car for a Gen 4, but I can't justify spending the money when my Gen 2 runs perfectly.

Another, less important problem, is that when I raise the liftgate, it now squeaks. I have put some silicone spray on the lifters, but that only helps for a very short time.

 

This is a follow up on my original post on the problem of unlocking the lift gate. I took my car to my usual auto service place (an independent, not a Toyota dealer). They said I needed to replace the entire mechanism, which I just had done. FYI, it's not cheap. The part, an OEM was ordered. It was described as "OEM rear hatch, garnish/handle" and cost me $438. Labor to install cost $86 and took half an hour. Add taxes and some supplies, and total cost was$567. I've using this auto service for many years and trust their competence and don't think they were ripping me off. But as I said, it wasn't cheap. But now, yeah, the lift gate works great and opens with very little effort.

 

I, myself,did nothing except take it to my mechanic. The mechanic ordered, I believe, the entire unlocking mechanism and removed the original piece and installed the replacement part(s?).