The resistor in my link has a sliding tap on it. The same ad has a 5 Ohm 200 Watt resistor available that would also work. I'd move the tap to a position where the solenoid would work efficiently without excessively stressing the drive unit. There would be no need to use the entire capacity of the resistor. I chose that one for its heavy construction and ability to dissipate heat. Of course, it would only be in use for a few seconds, but I'm a believer in overkill whenever possible. It's also MUCH less expensive than a 12V solenoid.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!