Let-off question

[John Ross]

Hi List,
What might the problem be?
The hammer does not drop that little bit, after let-off.
If I weaken the spring, then I don't get the raise, after it comes out of
check, and I still don't get the small drop.
This is a grand with new hammers and shanks where the original hammers were
not available.
It is probably something simple that I am forgetting, old age. :-(
The jack is coming out from under the knuckle.
Best regards,
John M. Ross
Windsor, Nova Scotia, Canada
jrpiano@win.eastlink.ca