Am I stating the obvious here. The cure is simple. Write it up in the Tech Log and get the engineers to fix it!
What is not so obvious is that some aircraft (Cresco, Pac750 et al) are just prone to nwheel shimmy regardless.
An operator in WeeWaa told me that the best way to prevent the shimmy is to pump the scissor link full of grease often and it is less likely to suffer, but as others have stated, stopping it immediately it occurs is paramount.
On the 210 the shimmy can be prevented entirely by using judicious back pressure to keep the weight on the main wheels at any speed above 40 knots.