Toilet --- lazy flush

[Bienes Raices]

The tenants are concerned that the toilet does not have a powerful flush.

The water goes up to about a half inch below the fill line on the overflow tube. I poured some extra water into the tank (so that it went all the way up to fill line) and flushed and it didn't seem to make much difference. I don't the flapper is the problem either, since it isn't shutting prematurely.

I read to turn the water off, duct tape the jet holes under the rim, and then pour vinegar down the overflow tube and let sit over night to see if it will break up any deposits inside and improve the flush. Heading back there early tomorrow morning to see if that worked.

If that doesn't work, does anyone have any other ideas, before I give up and pay to have a plumber come out? Does the size of the jet holes toward the front of the bowl matter? I noticed these are all small holes. (I have too bathrooms at my own house, one with big and one with small holes, and I noticed that the one with the big holes has a stronger flush.)