OK, very good progress today. I went out this morning and found that the ball bearings on the actuator motor mounts were completely seized solid! Actually, I have never even bothered to check these... doh! So the actuator was working hard moving itself on very tightened bolts. A bit of WD40 freed both ends up, so it's free to move as it was designed....
Also, got rid of the self amalgamating tape(!) on the flanged bearing and replaced it with metal epoxy resin. This resulted in the bearing being sat very tightly in the hole as it was supposed to with the inner insert greased up and moving freely.
The result? Well, not 100% perfect but I would say 95%. The dish lands generally within 1% SNR no matter which direction it came from. I also somehow managed to squeeze 1 or 2% from a number of sats without modifying any of the alignment on the mount. JSC Sports HD on AB7 has gone up from 52% to 64% SNR! Unless it's a daily variation....
Also, noticed that if I squeeze the last of signal from MBC (Nilesat 101), JSC suffers and vice versa. Are they in different orbital positions? (7W and 7.2W respectively)