Double check it’s not loose screws holding it onto the deck or the hanger sliding back and forth in the baseplate. I haven’t yet found how to increase preload in this kind of truck any other way than putting a washer under it. Just loosen the screw, holding on kneeling on the deck leaning all the way over and stick it under.
Alankerr is selling some nicer sets of channel trucks for really great value, I got his silver ones. WTS (USA - MA) My Esk8 Vault is open - check it out 👀