After 4 plus years of use, my MacBook Pro was still running strong but the battery had become flakey. Running the MacOS System Information report showed that the battery was failing.
I ordered the battery as well as the recommended tools, since they reasonably priced. The repair is straightforward and the iFixIt repair guide clearly showed the procedure.
Work in a well-lit space, have a container to hold the screws that need to be removed, don't be in a rush, and follow the guide. It's actually a very simple repair that I hope will extend the life of my MacBook Pro for several more years.