Batterty Isolators - Is there a consensus?

Interesting reading here and perhaps someone can suggest a proper replacement for the battery isolator solenoid that came with my Winnebago Minnie. In the ten years we have owned this MH, I have replaced the solenoid twice, with the same model obtained from Winnebago. Last time was only a year ago, and already I'm having problems again. The problem I have is that the solenoid doesn't always pull in when the ignition is turned on and the engine running. With the ignition on, I get voltage at the coil terminal, but no action from the solenoid. I can see the house battery voltage readout on our inverter display when sitting in the driver's seat, and sometimes after driving over some rough road, I can see that the solenoid has pulled in so that the alternator is then charging the house batteries. After the solenoid pulls in the first time, I can use a jumper with the ignition off to connect the coil terminal to one of the heavy battery terminals and the solenoid pulls in and drops out normally, with a loud clunk in either direction. A day or so later I can't count on the solenoid working though. It seems that it gets stuck after sitting for a while.

The Winnebago supplied solenoid is a Trombetta #936-1215-011-21. Anyone have a suggestion for a more reliable replacement?