The document below does not mention a coupler adjustment nut/bolt.
Atwood Yoke Style & Flip Latch Couplers — Installation/Operation/Maintenance:
Text extracts from above:
WARNING - PERSONAL INJURY: For proper tow vehicle and trailer hookup, towing performance and to prevent damage to hitch and trailer coupling, the tow vehicle and trailer are to be level with respect to flat ground after hitching up. If your trailer is not level, equipment is available to raise or lower the hitch ball.
CAUTION - PRODUCT DAMAGE:
• Use caution when backing or towing vehicle for hook-up, damage to coupler may result.
• Avoid sharp turns when towing or backing. Jack-knifing could bend coupler or create extreme stress or fracture.
FLIP LATCH COUPLERS
PART # 88555, 88600 8,000 lb. Capacity
PART # 88007
, 88010 10,000 lb. Capacity
1. To open, slide forward and pull up open latch before inserting ball (FIG 10-A.)
2. Place coupler on ball of same diameter as coupler ball socket size and of same or greater capacity than trailer GVW.
3. When ball is completely nested in socket, push top of latch handle rearward until handle snaps into closed position.(FIG 10-B.)
4. Extend jack to ground and lift car/trailer combination 2˝-4˝ to insure coupler is securely attached to tow ball. Retract jack completely before towing.
5. Insert padlock through hole in handle
Note: These couplers are not adjustable for ball size
1. Lubricate ball socket and ball clamp with wheel bearing grease
. Clean and lubricate monthly.
2. Check towing hitch, ball and coupler for signs of wear before each trip. Replace coupler if damaged or worn.
3. Lubricate moving or sliding parts monthly with S.A.E. 30 weight oil