i have a 93 i/o volvo penta sp, the problem is that the throttle moves forward easily but when i want to go in reverse it take some force to make it go back, is this just from lack of use or is there some adjustment to be made???also i thought most boats had a way to rev the engine without the prop moving, when i move the throttle forward the prop goes right away, there is no switch to hold down on the throttle to do rev the engine without the prop going, any help?