Before I bought my new boat I had 4 Brutes on different boats.
There's really no tension adjustment but you can back the pinion gear off about a quarter turn to get a tighter fit to the rack. It that doesn't fix it you need new cables. The shaft bearings are also known to go out and can cause play in the steering.
It's hard to say what the whining is but I would look at water getting in the foot rusting a bearing.
The 6th speed is another off setting. It should look like a stop sign.