My control used to work fine, but now one lever is hard to move. What should I do to fix this?

First, determine where the problem lies. There are three possible trouble areas: the control, the cable, and the throttle or transmission connection. By isolating these one at a time, you will find the problem. 

Engine(s) must be OFF when performing these checks:

a) Disconnect the cable at the throttle or transmission attachment point. Move the throttle or transmission arm through its arc to be certain there is no restriction or binding. If the arm is stiff or binding, clean and lubricate moving parts. If this does not solve the problem, make the appropriate repairs. Generally, the force required to move a throttle or shift arm should be no more than 5-10 pounds. 

b) With the cable disconnected at the engine end, try to move the control lever. If it moves freely, the problem was the throttle/transmission arm. If the control handle is still hard to operate, disconnect the cable from the control. If the lever operates smoothly, the control cable needs replacement. 

c) If the lever is still hard to move, lubricate the lever pivot point in the control with waterproof marine grease.