got this diamond nr770h on my truck and its been working fine for months but now im getting high swr on 70cm. 2m is still good around 1.2:1 but 440 is showing like 2.8:1 on my meter. didnt change anything recently that i can think of. mount is still tight, coax looks ok. anyone else run into this with these antennas?

Check your connections first - corrosion can build up pretty quick especially if you drive in salt areas. Also those NR770s have a reputation for the matching network going bad after a year or two of weather exposure. Might be time for a new one unfortunately

yeah i had similar issue with mine last winter, turned out water got into the coax connector somehow even though it looked fine from outside. took it apart and there was green crud all over the center conductor. cleaned it up good and sealed it better with some good quality self amalgamating tape and been solid ever since