This Janome compatible 2 Pin Push In LED Light Bulbs is very small, we have moved away from supplying the Halogen Bulbs due to the excessive heat they create, drying out lubricants in the machine head. These bulbs despite slightly larger will indeed fit in the head of your existing machine be it more snugly! 
fits the following models:
Janome: MC3000, MC4000, MC5000, MC5700, MC8000, MC9000,  MC11000, MC4800, 4030, J150, MC3500, XC33, 
MC10000, Compulock (888).
*Appearance may vary