your machine requires Class 15 bobbins.
generic class 15 will work just fine.
i've used them for years in three different janome machines with no issues at all.
as to the needle threader ...
try using Organ brand needles.
the 7700 is one of the Horizon series machines.
the eye in Organ brand needles lines up more reliably with the threader's wire than other brands i've tried.
__________________
- necessity is the mother of invention. lazy is the crazy aunt.
