Here are the piece parts that make up the solenoid assembly. (click on each image to see full size).
When the starter button is pushed the copper surfaces on these two parts come into contact, energizing the starter. These surfaces burn/corrode/oxide causing poor contact. This greatly increases the amount of current required to make the beast turn over, hence the clicking. Cleaning will help, for a while. The long term fix is a higher power starter and stronger battery. Heavier cables will help, too.
You only use the electric motor and solenoid portion of the new starter, and reuse the front hear portion of your Rocket starter. I had to grind down the new starters' plunger rod to match that of the Rocket starter. Not a complicated operation.
Hi Gary,
I got mine from an early 2.2lt 4 cylinder camry. Pic with pink pen markings and the description in yellow and you only use the motor part (long bolts) the solenoid contacts are interchangeable but not the plunger.
Also open up the solenoid cover then remove the plunger, i also loosen the remove the contacts and linish/sand the contact areas and replace. When replacing before you tighten it all up push the plunger down onto the contacts to align them for good contact, I them use a sharpie or niko to coat the contact area and push the plunger down and give it a turn to reveal how much contact area i have then make adjustments as necessary.
pic inside the solenoid is how mine came new the contacts are not flat thus reducing the contact area.
Hope this helps
There is a great discussion on starter replace/repair at Inexpensive Starter Replacement
You should add your content there. You're the first I've heard to replace the solenoid and shorten the plunger.
Thanks for the link. I just ordered one to keep on the shelf. I checked the sticker on the starter motor and it confirmed Denso No. 428000-1810, Triumph No. 1310300.