They refer to the force required to open the door as " counterbalance". The force adjustment is a "counterbalance system" (springs). Page III
Section V, R2 & page 17 section 12 describe adjusting spring tension (counterbalance). Page 17 section 11 describes securing the door PRIOR to tensioning.
1*888*827-*3667 is supposed to be "a walk you thru it" customer service number.
This opener is basically a boat lift- (motor + forward reverse switch).
Momentarily pressing the Up/Down button activates the door. If an
out-of-balance ( caused by unequal spring tension) condition causes the door to stop while opening or
reverses the door while closing, apply constant pressure to the
Up/Down button until the door is fully open or closed. This will allow
the opener to move the door in an out of balance condition, until the
problem is corrected (see Troubleshooting). The Up/Down button
(when unit is closed) can be activated by pressing flip cover.
Go through the monthly maintainance page 45 ( probably never done)
This affects resistive forces too. Item 4 addresses "contact / obstruction". This is a second name for the force detection system (springs). It refers to "qualified service person" because if they let you know you can do it, and you get hurt or killed, they can be sued. So they don't tell you to make the adjustment. BUT they actually did tell you how in the Install section.
The short of it all: If grease and tighten hardware are not enough, tighten the spring tension a few notches at a time until it works properly.