I would start with a new gauge. Buy a tel-tru they are awesome! You might just want to get a Maverick ET-732. Gives you pit and meat probes.
Once you have a good gauge then start troubleshooting. I would not do anything until you find the internal temp of the meat chamber.
The meat looks great!
Rex's Red Hot BBQ
KCBS & MABA Member
and Backup Blue Thermapen
Superior SS1, Traeger Lil Tex, Weber OTS, Weber Spirit