Cable tv experts: how do you TEST those CABLE LINE SPLITTERS, the ones that split the cable to go to 2 tvs?

so i have a bunch of these all over the house, and i know that every time a tech comes out if the picture is not clear, the first thing they do is change those splitters. but how do i test these things with a electronic tester? i know i could run lines to 2 tvs, but there must be an easyer... show more so i have a bunch of these all over the house, and i know that every time a tech comes out if the picture is not clear, the first thing they do is change those splitters.

but how do i test these things with a electronic tester?

i know i could run lines to 2 tvs, but there must be an easyer way

thanks!

oh, and is there better ones (brands) than others?
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