Trouble with a sihi 3408

[MN Jake]

I really hate asking this!!
Left after maple season last year to do birch several hours away. Forgot to drain the sihi vac pump for several weeks after. I did drain it and filled with glycol. Never thought to spin the shaft at that point.
Shaft is stuck. I’m fairly mechanically inclined. How much trouble am I in? Have any of you torn one apart?
I have about a week over here maybe more
Thanks in advance for any replies!

[WMF]

My Sihi 3708 is stuck every year even though it is stored with glycol. I panicked the first time it happened then sat back and analyzed why it is stuck.
The rotors and housings are close tolerance and even the slightest corrosion at the outer diameters of the rotors will make it hard or impossible to break the shaft free by applying just rotary torque alone.
Took a large sledge hammer (10 lbs)and LIGHTLY tapped the end of shaft on drive end of pump and then LIGHTLY hit cast iron housing from both directions in same plane as shaft. The idea is to make the rotor move within the housing a few thousands and it will break the holding corrosion free. A pipe wrench can be used to apply some torque to shaft and is safer than trying to start it with drive motor.
This works to free every stuck Sihi I have ever tried it on including several brand new old stock pumps from Ebay that were very cheap because they were stuck.
After the shaft breaks free there may be a slight rubbing sound as the shaft turns but it will be gone after pumps runs.
I have never seen any damage or reduced performance from a stuck pump after it is freed up

[MN Jake]

Thank you WMF!!
I was crapping tacks over here!
I will check it out tomorrow and post back!

[MN Jake]

Thank you for your expertise WMF!
I did what you said and it went exactly like you said.