OUTBOARD MOTOR VIBRATION ONLY AT LOW SPEEDS

[fdheld34]

Thanks all for input......
this is a new to me rebuilt motor and I got prop from my neighbor..believe it is a 15x17p (again stainless but dont know the brand) The motor has good compression spark etc.
I was wondering if I could run on hose with the prop and put in gear and push throttle until I felt vibration and then do it without prop on motor to see if a difference....would I be at risk of damaging motor by putting in gear and revving up???? without being in water and without prop on shaft?? I will look into having prop balanced straightened etc. but want to run some type of test first to see if this is the culprit...did search on google and no real definate test has come up for this problem!
Thanks again
Fred