Toro Reelmaster 3100-D Service Manual page 303

15.If counterweight was removed from cutting unit,
install new O−ring on counter weight. Secure counter
weight to cutting unit side plate with two (2) flange nuts.
Torque screws from 27 to 33 ft-lbs (37 to 44 N−m).
16.Install cutting unit to the machine.
Reelmaster 3100−D Page 8 − 33
DPA Cutting Units