A slightly loose hinge pin would not cause a previously accurate Encore to suddenly shoot 5-6" groups at one hundred yards. Neither would loose thimbles: The thimbles on my Encore have been loose since i bought the gun, it has not caused any problems with accuracy.
I took the rifle to my local gun shop and had replaced with steel and also told them to check the base while they had the scope off.
There is something wrong with your scope, scope mount or rings. It may be related to your trip to the gunshop.