You might look at it this way;After three years, you likely got ur money's worth from an inexpensive pistol.Maybe buy a new one, keep the first for spares. Comparing the two might show where the first went bad. Can't tell you how to fix ur problem, never experienced it.
The lowest price you can expect for a Beeman P17 in Europe today, if I'm not wrong, is 79€ + shipping. That's about 94$ + probably 20$ for shipping. An HW40 (Beeman P3) can be found at 176$, shipping not included. For me, this justify my efforts.
I feel I'm slowly crossing the line between being determined and stubborn . Now I can cock and shoot that pistol when the right "side" is opened but when I close it, thing goes back wrong ....Yves
...So I'm going to give myself some time for ... getting a little calmer, forget this ¨%§/ů!. problem, gently store my P17 for a while (that won't hurt), shoot my Crosman 1377, 2100b, Vantage NP, and my Webley Rebel aka Airstrike blunderbuss a bit more often, and everything will be OK...