I've just read from the beginning. I've had dxi6 for many years, well into double figs, I'm using dx8, gen 1 and gen 2, and nx8, with planes, so I know the transmitter quite well.
When a model is set in the memory, it won't get lost if the batteries get flat. I store my dx6i which is for boats without batteries, for many months, pop the batts back in, all the models are there in the memory.
The scroll roller is a problem if it starts to malfunction. It might be that, and the on off switch can start to malfunction over time. I've had both issues, the roller can cause model memory to jump. Don't disregard it until logic have looked at it. If they advise against a fix, they usually won't charge you. It's a great transmitter. Just be mindful 2.4 ghz doesn't like water so mount your receiver above the water line or you could get signal loss, and remember the hull will roll in turns.

Hi Eric,

You may not have any fault with your Spectrum tx as the Sea King ESC is a "forwards only" type - it has no reverse function!

This may be causing you some unnecessary concern.

If you are familiar with how to "call-up" and "lock" a new or different model (or function) into your Spektrum radio, it should not loose its memory or switch to a different model.

Any function (including model selection) that is not "locked-in" will not be retained when the radio is switched off.

Check you have good batteries in your TX that are providing a strong current as this can cause you some problems if they are weak and unable to deliver enough power to support the function of your transmitter. (see Steves-s previous comments on this thread ).

I have several older types of Spektrum transmitters than yours and none of them loose their settings, but if you are not familiar with them, you may not be aware of the way they can be asked to change .....and retain ....their settings?

If you do not already have one, I would suggest that you get yourself a copy of the owners handbook for the Spectrum DX6i and read it carefully so you understand how it works and functions as they can be very confusing - especially as different manufacturers programme their transmitters in very different ways.

These manuals can be found online if you cannot find a hard copy to buy.(see the comments by Mark Stoney on this thread).

Model boats have by far the least demanding use for a very capable radio like yours as you will not have any use for most of the functions that it has to offer, but you should be able to use all of its memory functions - including using it for as many models as your DX6i can store.

Don't worry, your radio is probably doing what it should and may not have any faults at all.

If you have a local model shop or local radio control user who is familiar with the Spektrum DX6i radio (or any Spectrum or some JR radio systems) they will be able to help.

If none of the advise offered here by all the contributors helps, then try contacting Logic RC again to explain your problem and ask if they can give you a price for servicing - and possibly changing the internal memory capacitor if it has failed.

Bob.

I’ve followed your suggestion @mike stoney, thank you! One boat per radio is the way to go.. now got a problem with trying to program the ESC that came with the boat! Will open a new chat.

Thanks RogerA1, I rang and got the correct email address (support@logicrc.com - but had a reply from spektrum@logicrc.com) with the following reply:

Hi Eric

I would say with out seeing the radio it’s a main board issue the issue there is if it is the boards are no longer available so would be unable to fix.
You are welcome to send in the radio for investigation

Regards
John Norris
Logic RC
www.logicrc.com

That’s that then! Being sold for spare or repairs!
Thank you all..
Eric

Logic RC phone number correction I missed a 5 from the number should read 01992 558226

Hi Eric
Sorry missed a 5Number is 01992 558226

Thanks all for the really helpful suggestions, particularly the link to Logic RC - RogerA1, could you check the telephone number you listed please? Looks like there’s a number missing..

Logic are the UK appointed horizon hobby service centre, great service, very fair prices

That is good information Roger - a good UK service centre for Spectrum is just what we need - thanks for the "heads-up'.👍

Bob.

I have an old 6I which had problems with the digital Trims
Spektrum repairs had been transferred to Germany.
I found a repair company in Hertford called Logic RC Ltd
They were absolutely brilliant fast service and very reasonable price. Tel 01992 58226