Difficulty plugging in

I have a 2013 Plug In Prius here in the mts. of Colo. I have gotten 71 mpg for the first 30000 miles. Very hilly here. My question: It has become ever harder to plug in the charger. First my wife complained she could not do it, and now I am finding it harder too. I tried some silicon spray, but that seems pretty irrelevant.

Now, I see how the catch works. Is there something that could be filed down just a little to ease the process?

Amusing note is that I think they are STILL not being sold in Colo. I got mine shipped from Seattle.

 

Many thanks for helpful comments... will pursue one of these remedies....

WOW: Piece of cake. The O-ring is red rubber just inside the "plug" -- the male piece that is attached to the house, not the car. It comes out with no problem, and now the attachment is extremely easy, if a bit loose. I suppose the downside is that the looseness might cause a disconnect, but that has not happened yet. THe O-ring itself seems to have become a bit misshapen over time, which is what caused the problem. Anyway, very easy fix!