Looks like you have a dirty J1 stick (the potentiometers). Have you tried to clean the left stick yet? Have you "stirred" the stick to see if it improves?
Typically, most pilots will clean them with a contact cleaner spray (no oil) when they see this.
BTW, the potentiometers can oxidize in certain environments over time.
Please respond and you'll likely get directions from several pilots on how best to proceed with the cleaning.
You could also do a search in the forum to find previous posts on this.
