Vibrating without blade engaged

[Changy]

I had a call from a person who has a Honda mower. She is unsure of the model number but says it vibrates when she starts it. When she engages the blade, the vibration settles down. I think it is probably a bent crankshaft but I'd appreciate input from others. I am in a tricky position because she lost her husband and the mower was his so she is keen to keep it.

I suppose I could try and source a secondhand engine and drop it in. She is a fair distance from me but I don't want to let her down. Sadly, none of her local businesses are interested.

Any thoughts, other than I am a sentimental fool with too much time on his hands?

[Mick]

Does sound like a bent crankshaft, it's pretty common to be honest.  Easily diagnosed by sitting machine on its side (Dipstick side down and spark plug removed) Just pull the starter rope and you'll see the blade wobbling like mad.

I have successfully straightened many of these over the years and got them spot on. 

[Changy]

I visited this lady when Storm Ashley had passed through. It's a 2160 Honda and the shaft is bent. I learned that someone had cut her lawn and somehow managed to hit both the blade and the deck. Perhaps they tried to mow her rockery

She has agreed to get another mower, and wants me to sort a second-hand one that I can bring up to a good state.