Error 29 adjust tx sticks help

[Phantomcal]

Hi I've been looking for a solution to my problem I have the stock tx I get error 29 flashing red led on start up and then can't engage the motors when I've looked on naza the tx channels all center but on the bottom one marked r it wont go all the way to 1000 only gets to -895 so I'm assuming this is the problem I've tried centering and power cycling but nothing tried calibrating sticks nothing how do you adjust the the stick or trim any help would be appreciated thanks