Problem replacing screen taps with pots

[TinCanAlley]

Okay, I'm obviously doing something wrong, so here's the deal.....

I'm trying to replace the screen taps with pots so I can better control the color for grayscale, etc. I've looked over the schematics (see attached) and came up with the need for a minimum of a 4K pot. I purchased three 5K pots and tested each one. They all are just at the 5K value.

Today I decided to test the red, so I took off the lead from the red (it was on Med) and put a jumper on the lead. I then put a jumper on the HI output. From the schematics, the HI should be directly from the collector of the red video output. On the other end of the wire lead, there is a 1K resistor and then it goes to the CRT socket. When I put the pot between the HI and the lead, the color gun came back and was very red. I expected this as the pot was fully CCW. As I rotated the pot, the red barely changed. I went full 5K and the red was reduced so little I almost thought it wasn't working at all. I then put the jumpers on the two end connections so it would get the full 5K and it was the same.

So where am I going wrong? The HI tap is full, the Med gets a 1.2K resistor and the Low gets another 2.7K. If you add all those up, that's 3.9K. So why won't a 5K pot give me the same kind of reduction?

Thanks!