I received this question the other day…
We are having problems with material leakage between the nozzle and the sprue. Is there some way we can adjust this?
Note: after some further questioning, it was determined that sprue break was not being used, the nozzle position has been aligned, and the diameter and radius are correct.
Basically, you need to increase the contact force between the nozzle and the sprue bushing. This will often relate to the carriage forward force or position.