The Model 3320 is no longer for sale and was replaced by the Osmo1 or the OsmoTECH. Information is for reference only.
3320 Osmometer Impacting Information
On the model 3320 Advanced Micro Osmometers the impactor is held in place with a metal bracket. This bracket has a rubber pad to deaden the sound of the returning impactor pin. It may be that the flat top has stuck to this pad and can be released with downward pressure from your fingernail.
The rubber should be treated with French chalk or talc to prevent further sticking.
The diagram below shows A the cover screw to be removed after the power cable has been unplugged.
Downward pressure on the pin within the spring retainer D will relieve sticking.
The rubber pad is item F.
If further cleaning of the impactor is required the bracket B can be removed by loosening screws C. The pin with its spring and retainer (keep them in order) can then be lifted vertically from the solenoid body E. The pin should be cleaned with 70% isopropanol.
Note that on some units the washer as shown in the diagram below may not be fitted.