Hello guys I bought completely new Casio ProTrek PRG-600YB-3JF from eBay and I love it but it has a small issue which annoys me. All buttons on the watch work perfectly except the bottom left one for switching modes. That one works as well but when I try to press it its noticeably harder to press than others. Is this normal or a defect? If it is can I fix it or should I return the watch and buy new one?