I've been taking starters apart since about 1964 or so and guess how many times I had to take this one apart? I mistakenly slipped the yoke from the solenoid into the thing wrong and ended up with a perfect wrong working starter that only extended itself about halfway out. interesting to say the least. So to answer truthfully, all of this depends on how much time vs. money you can develop. This ratio makes all our decisions for us.

I happen to have so much time I actually babysit my grandaughter many days a week. This is caused by a very simple problem. I am disabled and have a hard time standing for more than a 15 minute interval, much less walking to any great length. Many other problems. Not worth noting here. I do have HUGE amounts of time and my hobby that I never had enough time for was automobiles. Used to dragrace and my dad was a top foreign car- race mechanic in his day. I do NOT however have a large amount of money to work with. My wife doesnt make enough?????

So my trail and error, and investigative methods are to save ME money and waste as much time doing so as possible so I dont go bonkers with nothing to do, or spend any money I dont need to.

I depend on many of these forums to help me and hope to help others some. Keeping me straight is a full time job, my granddaughter is distracting me right now.

it is entirely pssible that any other part of the battery system is breaking down. A single cell in the battery may be starting to form deposits that are keeping the battery from being as effective as it might be. A simple hydrometer used to tell us what was going on. these days batteries are supposed to be closed. They will work for a long time to a lower effectiveness than when new also. This could be one of the simplest reasons for your proble.

An alternator is also a piece of gear that will sometimes develop problems that cant be seen as easily as we think. If one is supposed to develop a capability of about 65 amps top and 20-30 amps when idling, it may well be that the alternator is developing quite a bit less power than it should. This is not even tested properly. Even the stores that test these things have equipment that is interpreted by its operators as either showing a working altenator or not. This is not really a proper test to prove a weak alternator. All you can do is look at the parts that are the oldest, have them tested by the best shop you can find and take their advice.

A battery that is 3 or 4 years old is already a problem. At least a normal price one. Any alternator with 50,000 miles on it could be starting to give trouble. ALL guidelines have their exceptions. Anyone can tell me I am wrong. These are some simple guidelines. The one thing that is true is that the starter is always affected by the rest of the system. The rest of the system wuill cause early starter failure if not caught in time also. So even if a new starter seems to cure the problem. Be sure the rest is working or you may buy a new starter two or three months from now.

A new starter can quit cause your engine leaks some oil on it. Predicting a starters life term is next to impossible. If you live on a dirt road, yours should last less time, etc. Driving through puddles may cause rust or even clean out lubrication, yet it may clean out the same sand from your dirt road, thus keeping it running longer. No way to predict.