I see that no one removed the cap cover and opened from outside? So the filler cap whis is in color of the car can be removed by sliding to the rear of the car, than you see internals and with a flat screwdriver you just push up locking pin. That is how I solved my problem. Good luck to all.
I would imagine it would be very difficult to replace without a tool but it could be possible. You can try cutting the old belt in half lenght wise and then putting the new belt on free half of pulleys and finally removing the old one completely and just pushing new one in place. Seen it done...
We learn every day. If i undrestood correctly i should leave it as is for best performance, shouldn't I? opening it fully will kill my low rpm performance? There is a lot of useful stuff in this forum i have been reading for last 3 days