@elfkin when I got my current sewing machine (a modern domestic one, in the same Singer line, but mechanical rather than electronic) the first thing I did was reading the manual, not finding anything about oiling it, going back to the shop, asking something like “ok, where am I supposed to put oil in this thing”.
They explained, and since then we have been living happily ever after :D
(the case wasn't sealed, however, it has easily accessible screws)