84 Mercury 75hp neutral throttle locked

[Pigith]

I bought the boat last year from my brother runs great but this year noticed th neutral throttle stops about 1/3 from full. Pull it back put in car goes 100%. My brother thinks it’s stuck I can’t remember but I think it would idle up higher in neutral than 2k rpms. I can’t find any info about it anywhere. There are also 2 screws friction and detent? Wording might b wrong I’m not home and can’t look at that one I google it and people were talking about forward and reverse I only have one and it’s 1 inch I front of my throttle handle. I’ve also been told maybe it’s locked to not over rev motor. But we can’t remember so looking for some info. Thanks.