There is s time-honoured, fix all method of "servicing" a Dometic refer called "burping".
The good part: it's pretty well free to do.
The bad part: you need to remove the refer from the trailer to do it.
Remove the refer, take it out of the trailer completely, and turn it upside down. The recommended length of time it should stay upside down varies widely, according to what I've seen here on the Forums. Some people have said as long as overnight, while I've seen others say twenty minutes.
Anyway, choose your length per side, and turn it every <length of time> until you have had it on its head, on the left and right sides, and then upright again.
Re-install it in the TT, and keep all fingers, toes, whatever crossed while you turn it on.
You might want to do a search on "burping" if you want more detail...
Yes, it really is a valid way, but sometimes it works, sometimes it doesn't, and yet other times, it seems to be only temporary.