The link below is for a sold machine, but has some good info and pics. If it is a modified Juki, (as the seller says), then you would oil it as you do any machine. Your OP saying "check the oil" has me stumped...if it has a dipstick, (like the tin lizzie's do), then there will be a mark on your dipstick..if not, just oil it at all of the oil points you would oil any machine.
https://forum.apqs.com/topic/40540-t...lting-machine/