nope, you should worry if the old grease starts to get forced out!

used to be that the line of thinking was to force out the old grease when you put new in. but the design of newer things means that you are breaking the seal when you do that.

on my tiller i have put grease in it probably 7-8 times inthe 4 years i have had it, and never yet seen any come out.

Ok, that makes sense.
Sometimes it is hard to shift from neutal to any gear.
Does that mean there isn't enough grease?
The manual is not very explicit.

Hi jerseybob, grease away. Youhave the majority of the volume of that gearcase to fill !

NEVER leave it outside if it could get rained on, ere water goes right down the seam and rusts the innards or shift shaft.

If I had a new one, and had a sticky shifter, I would put a whole tube of a GOOD ag type grease with low viscoity and high wter reesistance into it. I use a chevron pink colored moly ep grease tht rocks!