Im very happy with this engine. comes with all the spares to upgrade nearly any sewind machine's engine.
Only reason i put 4 stars are:
The needle position controler fixing screws does not fit my Juki 5550, so i had to make a different solution.
The cable protection cap is a little loose in all the conectors that go to the driver.
Top tip:
Cons
You would need a new belt in most cases
Instructions are good enough, would be better to explain in detail how to change the settings
Pro's
Very nice that is has a 45 mm pulley for extra low speeds
kneedle position control is amazing