You should change your outboard motors impeller every 100 hours or every 3 years, which ever comes first. If you’re handy you can do this yourself in an afternoon. The smaller the outboard the easier it is. For large outboards, 90 hp and above, get a helper to help you remove the lower unit because they can be heavy, especially with the stainless steel drive shaft.
All Outboard manufacturers are slightly different but remarkably similar. Your bolts will be in the same general location and the steps are generally the same. I recommend you get a outboard motor shop manual for your specific motor as a guide.