The problem you have is caused by the notorious image sensor defect due to faulty CCD units (manufactured by Sony) having been fitted at the time of manufacture, with this affecting a large range of models distributed worldwide.

JVC ran a free repair offer on this problem for about four years although this expired about two years ago now, all I can suggest is that you contact JVC customer services appropriate to where you may be located and explain the problem to them, which I will say they are well acquaint with!.

Since the free offer expired I am aware that JVC have occasionally carried out a free goodwill repair for some people, but beware as if its not done on a goodwill basis the charge for the repair (a replacement sensor) can be about nearly half the price of the unit when it was first purchased.

Sensor replacement isnt a big job for anyone used to working on small electro mechanical devices, and if requested I can supply full details on how to carry out the work should you feel able to carry it out.