The third category, which nobody mentions until something leaks: the rubber parts wear out and they are cheap.
The group gasket, the seal the portafilter locks against. It hardens and shrinks over a year or two. Symptoms are having to turn the handle further round than you used to, and water seeping around the edge during a shot. Replacing it is a few pounds and about ten minutes, and it is the most common thing an owner can fix themselves.
The shower screen wears and clogs. Also cheap.
The steam wand tip blocks with milk residue if it is not purged and wiped every time.
A realistic schedule for a daily machine: water backflush after the last shot, wipe and purge the wand every time, detergent backflush weekly, screen and gasket check monthly, descale on a frequency set by your water, gasket replaced annually or when it hardens.
That is a few minutes a day and an hour every so often, and it is the difference between a machine that gets replaced and one that gets repaired.
On your immediate situation: do the backflush and the screen this weekend, get your water hardness figure, and plan the descale for next weekend once you know what you are dealing with. Two years is not too late, it is just overdue.