The bird at 129W is on its last legs... The signal level varies much more on it than any of the other birds they have up. I took the following signal measurements from 129W, 110W, and 61.5W using a D1000 for 110/119/129 and a D500 for 61.5W.
Notice how the signal goes up and down much more on the 129W transponders. The two graphs on the left are from 129W. The upper one is TP27. Much lower than TP . These are ploting signal strength in dB, so every 3dB drop is actually half the signal power (dB is in a log scale). TP31 is about 3dB higher than 27. TP31 on 129 varies more than 1dB in a 3 minute window, while TP27 varies almost 2dB! This is something that is uncorrectable on our end (unless you get a bigger dish to bump the signal level higher).
Compare that to the plots from 110W and 61.5W where I got at most 0.5dB variance over the same time period. This is what all of the TPs should look like. Currently I have little to no wind and not a cloud in the sky. I should not be seeing just large swings in the signal level on 129W if it was healthy. I have my D1000 peaked for 129, so thats why my 110W level is a tad low.
Edit to add:
Basic reading of graphs: Higher dB SNR is better and you want to see a nice straight line across, in optimal conditions.