Yeah your thoughts about the pickguard sound real, seems like the former owner wanted to isolate the pickups (the pickguard is made of iron)
Thank you guys! Now I`m sure enough that my investment is not wasted.
As fot the sound I totally love it, it seems like i've found exactly «mine». Sound is full of sparks when using both pups and the guitar sounds really deep but still clear on the neck pup. As for the bridge pup I use it only when I am Jack White in my garage.
Before this I used telecaster american standard and telecaster 72 deluxe, I liked both, but the first was too bright and the second was too muddy. Jazzmaster combines the two.