This year, I cleaned and serviced the fireplace and chimney. I purchased a chimney sweep online on Amazon. During the service of the fireplace, I discovered that the baffle plate had warped from overheating (see pics). I was able to order a replacement after tracking down the model number of our unit from the store where we purchased it in 2015, Custom Fireside.
I replaced the part, cleaned the chimney, and tidied up the inside of the fireplace. The condition of the chimney was good and not overly dirty, considering it hadn’t been cleaned since 2016. I should inspect it every year, but I believe I only need to clean it every five years, unlike what you hear from others. I guess it all depends on the type of wood you burn and how you burn it.
Our unit: Large Flush Wood Insert (Rectangular) with Hybrid-Fyre™ Technology
First two pics are of what was in the fireplace, clearly warped from over heated, last pic is the new one.