2003 Cobalt 200 throttle question

I think the trim switch is going bad in my throttle. Sometimes it works sometimes it does not.

Also the throttle is getting sloppy and I can not get it to just do the throttle anymore and not the drive - I used to be able to push in on the little button and I could give the boat some throttle to warm up - this no longer works. It still pushes in but it does not affect throttle rpm when I move the throttle itself

I want to replace the entire throttle assembly but was wondering what everyone recommends for a replacement and also if anyone has any directions for how to remove the existing throttle and replace?

thanks