I just got my Babylock back a couple weeks ago. It was $100.00 for cleaning and repairing the up/down button. It was around 15 months but I hadn't used it much. I feel I have invested alot of money in this machines so it should be maintained, as a car is.
I try to make in annually.

My machines go in once a year usually during the summer. It's a slower time for the LQS so a quicker turn-around time. The first year cleaning is free.

My Bernina dealer recommended once every other year. That's pretty much what I've done. I do a lot of maintenance myself. My new Bernina needs to be oiled in a couple of spots and I do it religiously.

This is my practice with my Viking as well - about the same vintage. I usually take mine in when I know I am going to have a reasonable amount of 'down time' with my machine.. planning; shopping; cutting - so it doesn't impact my sewing so much. And my shop is pretty quick with turnaround. Usually a week or less.

I clean and oil my machine as regularly as I can, my sewing machine guy showed me a few things when I had mine in the last time because he's an hour from me and getting it in when an issue crops up is a very hard thing for me to do since I don't drive. Before that, I would take mine in once every couple of years. Mine is vintage and I've always worked on vintage machines, so servicing them myself saves a lot of time and money.

I’ve had my Bernina 440QE for ~15 years and it’s been in the shop for cleaning and maintenance 3 times. I didn’t use it that much until I retired and it’s in the shop now for two reasons. I wanted to order a new tray for it because my cracked again and the shop owner told me Bernina decided that was a design flaw so the next time it came in for maintenance, they would put a new tray system on like the new machines have. It’s much sturdier and it locks. I waited for the backlog to clear out before taking it in. The second reason is I got a new Bernina 590 a couple of months ago and finally got it fitted into my sewing cabinet (waiting for DH to do it!). Since I won’t be using it much, wanted the 440 cleaned. Also, thinking about loaning it to my BFF to use this winter so wanted it ready to go. Probably will take it up to the cottage for the summer. I think it’s better to use them than let them sit for months.

I am putting a lot of miles on this machine in recent months. It sat for several years before that. I can imagine that is adding to what is going on now. It will be going in asap. For now I am using my FW that I recently had serviced. I did the majority of the tune up on the FW but wanted a pro to go over it for me as I am not confident in my skills with tune ups. So far so good. My Janome will go in asap.

I have never taken any of my Janomes in for cleaning or maintenance. I clean them myself. I also ordered maintenance manuals for all of them. I also take my machines and put them on a towel on a table and take the bottom off to clean and sometime grease with Janome approved grease in areas shown I the manuals, they only thing I do after each project is to put a drop of machine oil on the wick in the center of the bobbin holder. I would take my machines in for technical/computer issues, but never have had a problem with my Janomes.

Thanks for all the input. I don't feel as bad about it going down now. I will be getting it in for repair asap. Who knows. I know I have the manual here somewhere and should see if it says anything about service or longevity.

My large one goes once to twice a year. My cheapie has never been serviced but I am meticulous cleaner