I bought an Eversewn Sparrow 15 this past summer. It is an all metal/non computerized machine. It began making a racket and when I checked the manual, the only thing about "noisy machine" or oil had to do with the bobbin casing area.
Didn't help... I eventually took off the cover and oiled (I don't know what to call it) the top bar and oh what a difference. But there are no oil locations like I'm used to...
I guess we are out of it and not expected to do simple maintenance any more. But I was willing to void my warranty on a $200 machine rather than take it in for service. My fancy dancy Bernina 820 (the computerized crummy one) died for the last time. In the last 7 years I've spent about 1k on maintenance and fixes and had a year of down time going to the shop -- not even counting the year they were closed for Covid. And though all of this, my vintage machine older than me (I was born in 1960) has cost me maybe $200 in 30 years buying new bands every now and then.