The wording is a Bed Tilt. And this is common on larger Winnebago motorhomes.
And, so are air mattress problems. You can either try to fix the current mattress or buy a new one. It's called an I-Deal Rest air mattress but they are out of production now. Though I think parts are available.
Here's a YouTube of someone that fixed one - I don't know if this repair applies to your issue:
There are companies that will make you a custom sized mattress for your Tour. If you have a King sized mattress in your Tour it is not a standard King size. It's narrower and shorter than a standard king.
You can buy a California King mattress and it will be the right width but too long. So, a custom mattress may be your only option. Try
www.matressinsider.com to find custom RV sized Kings.
I have one of these RV Kings with a bed tilt function. I had a couple of issues with the air mattress and I pulled it out of the RV 4 years ago. I put in a California King foam mattress from
www.leesa.com. It was about 2" too long so I removed the headboard and that fixed everything.
People warned that the tilt function may ruin the mattress but it has had zero effect. It works great. The Tilt has not been an issue at all and it's been 4-years.
If you get a custom made mattress you'll not have to worry about the headboard.
Here's my Lessa Mattress after I removed the headboard and installed the mattress from a Box.