Yes, first of all if you do not need the 8 output splitter, bypass it in favor of a 2 outlet splitter. The two output has a loss of about 3dB, while the 8 is more like 10dB loss, and that could make all the difference.
If you're getting problems with one location only, check the cable for corrosion, etc. Since swapping the tuners left the problem in one place, try swapping the inputs on the splitter if the trouble swaps, it may be a bad port on the splitter, of trouble stays put, it is the cable or connections.