Update... today in freezing coastal wind, I took everything down. Made sure the pole was plumb and vertical, took apart the motor and got rid of the hardware limiter, which allowed me to take the dish to 68.5E.
Now, the mystery with the strong satellites is now deepening. When I had my sat meter on the fly lead straight from the motor, the signal was off the scale on the usual Euro-sats on the meter's LCD screen. Cool, I thought.. Had a look on the Uno - yep, nice and strong. Checked the weaker sats - stronger than I ever had them on this dish. Great! Disconnect the meter, connect it up straight to the box - signals for weak satellites remained strong and for Euro-sats, they've all gone down again!
The problem I seem to have is the very short cable run from the dish to the receiver. It's only about 4-5 meters, which explains the stronger signals on weaker sats as there is less attenuation. But it seems like the Uno is getting overloaded by the Euro-sats and somehow shows a weaker signal. I connected a 10 meter cable in between and the signal for the Euro-sats jumped up (but still not as high as with the meter connected) and the weaker sats barely changed!
Some statistics:
5E - 12034H SNR 53%, 12054V 57%, 11919H 54%
26E - 11919H (MBC) 43%
53E - 11044V 60%
62E - 11682H (Aden Live) 41%
66E - 12565H (Mir) 48%, 12596H (NNTV) drifting in and out of lock - can't receive anything else
68.5E - Most Euro-beam TPs in 45%-55% range
For stronger sats:
28.2E - 10773H (BBC) 73%(!), with the meter in 86%, 10964H (Ch5) 99% ... why this difference?
19.2E - 10729V 65%, with the meter in 86%
13E - 12597V 64%, with the meter in 80%
Has anyone had this issue before - especially on the Uno?