Product review (5 stars): Works Great, But Make Sure Your Timer is Not Bad
This product works fine, but a word of caution - problems with the solenoid are often due to a bad timer.  Apparently, a bad timer keeps the solenoid activated too long which will melt the plastic around the metal post preventing it from freely moving up and down.  A new timer is $150, so if you have to replace both the solenoid and timer, you could probably buy used dishwasher from an appliance vendor.