We have a Jetpack Mifi 8800 that I think is wearing out after much use. The resolution on the TV is often blurry now even with an excellent signal. Up until a month or so ago all was fine. I bought a Verizon new in box identical replacement on Ebay. I'm wondering if I can simply switch sim cards. I'm not very tech savvy. I got this unlimited plan just before they discounted it and my biggest fear is I'll screw something up and loose the plan.