First of all, the easiest thing to check are the accoutics. Move the drums to another position in the room.

Then after that, if you can, change the positioning of the toms on the hardware. Sometimes raising them slightly can change a lot of things.

The next thing after that check the tuning. (I'm trying to do this in order of least effort first. It does sound more reasonable to check the tuning first, but I bet you can slide the set over four feet or raise the center post in less time than you can tune two toms.)

Then if it's not one of those, then it's probably with your resonance heads. and it's not necessarily that they are too loose. They could be too tight, also. But if after playing around with those for awhile, if you stil can't get it to your satisfaction, then I would replace them.