REX sewing machine. how do i identify what model...

Question

REX sewing machine. how do i identify what model i have? i have found 2 different #s one is 345 2L and the other is S766920 the plate on the back says made for REX by Nakajima. i need to know how to thread it and lubricate it. it has a lubrication tube with oil in it but it is loose from one end and i don't know where to conncect it. this machine was given to me and seems to run strong and smoothly but i don't know any thing about maintenance, etc. where is the best place to find a manual.
thanks
ron stalbaum
ijamsville, md 21754