SAB Solo Single Tuner Timeout for Tuner Lock Error - Please Help

Hi All,
When scanning the ABM i'm getting an error "Timeout for tuner lock", Then a of of the channels are missing from the auto bouquets or showing N/A,
This is now happening on 2 of the same boxes that i have, these were working perfect up to some weeks ago, The feeds & the satellite are OK because when i put another 3rd box onto the satellite cable i do not get this issue,works perfectly on a 3rd box.
I did notice on the 2 boxes that this issue is occurring on that when i do an automatic scan of the channels approx 540 channels are being found,
When i use the 3rd box that is not having this issue over 900 channels are being found,
Can anyone help fix this issue i have tried everything, new image , changing configuration settings etc,
I'd really appreciate some help on this please

Thanks in advance

Quote from codar

Can you give more info, image on receiver thats not working/ working?
You could try updating the sat xml file or do a full scan, (see if that picks up your "N/A" channels) before running autobouquets.

The Image is OPEN PLI, how do I update the satellite.xml file & where is it located please,
Thanks

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It is straight to the LNB, It is a single tuner so I only have tuner A