ok, so it looks like the one that says 87a is also 30.
I will buy a quality one. I bought one back at the beginning of this from Amazon. That's the one that stopped working. I trust Klein products. I think I get one of those.You have invested this much time in it, you might as well see this through. You NEED a meter to do electrical work. Trying to do it without one is, as Yoda would say, "not do".
You do not need an expensive meter. Just about any meter can measure 12V DC accurately enough. You should be able to find one locally or on the internet.
This one is good enough, but the batteries are a pain.
This is a much nicer one that uses more normal batteries.
Klein Tools MM400 Multimeter is an auto-ranging multimeter that measures AC/DC voltage, AC/DC current, and resistance. It can also measure temperature, capacitance, frequency, duty-cycle, and test diodeswww.homedepot.com
There are even more expensive ones, but they probably won't help you at all. The auto ranging ones are easier to use, but not absolutely necessary.
If give up now, all the time you spent will have been wasted. The meter will help you figure out what is really bad instead of just throwing parts at it.