PhilC - yes my first thought about things like RTV was “what happens if I get some inside the compartment?”.

I figure the sheath coil on the existing temp sensor will help me work out where it’s supposed to go. Next time I see the machine I’ll scout around and figure out where it goes. Shouldn’t matter for this stage of the project but it’s good to have an idea for later.

Thank you for the direction to REPCO etc for the rolls of gasket material. That will make it easy.

Ok, I bit the bullet and decided to tear down the starter motor myself and inspect it. I had a crack at it and despite taking the main through bolts out I couldn’t get it apart. So I hit up YouTube and found a gentleman doing a refurbishment on a very similar design 6 volt starter motor. Armed with a little more knowledge I successfully got it all apart and can now give it all a good clean.



However I noticed the following - and I have been wondering about this from when I first pulled the starter off: there is no return spring on the bendix gear. I couldn’t understand how the gear was meant to disengage from the flywheel if the pony motor didn’t start - and I have seen that it doesn’t when I was messing around with it last week, so I know this is an issue. I’m wondering if the return spring is missing? I don’t have my parts manual with me currently to check, but I also don’t remember seeing a return spring in the 6 volt starter parts break down.

The video I watched, that starter clearly has a return spring to push the gear back…

 

But my starter doesn’t have a spring. I think that it should have a spring…

 
 

The thought occurred to me that this solenoid may be a 6 volt solenoid (since its on a 6 volt starter motor) and the 12 volts that I put through it when testing may be the reason why it failed.

 

So I'm going to replace it with a 12 volt unit instead to avoid future issues.

That or I'll just directly power the starter motor and avoid the issue altogether.

It is just a continuous duty solenoid. They dont usually care what voltage it is to trigger them. Also your bendix never had a spring they were just thrown back from the pony starting. That other bendix you showed is a different style. It alos looks like the bushing hole in the nose end is worn egg shaped. If that bushing is worn will cause all kinds of maladies.

that armature looks on the rough side too...shouldn't be any discoloration of the copper and where the brushes ride...no dark segments...
-was there any pixie dust (solder) on the field coils? if so, usually indicates excessive cranking, toasted it up etc...

Kracked1 - ok, well that may just mean that the solenoid was on it's way out anyway I guess.

Well that's a relief to know that this starter never had a spring, just have to live with the unreliable disengagement I guess.

Thankfully the bushing hole in the nose of the starter is ok, it's just a rough casting and the angle of the photo makes it look bad!

Kittyman1 - yes I'm going to give all the components of the starter a good clean up. No, there doesn't appear to be any loose solder laying around in there, so I don't think the starter has been abused, just a git of wear on the front edge of the bendix gear which seems reasonable for its age.

Starter Questions"
How much "kerf" is between the sections of copper on the armature - should be a seperation. You do not want to short those segments out.
Any Starter/Gen shops in the area - armature can be checked with a "growler"
What condition are the brushes and associate compents of them - springs, leads, etc?

Bendix -- the way that is made - it relies upon the ring gear to spin the starter gear back, just like unthreading a nut on a bolt. Depends upon which is providing the driving forces.
Dry graphite lubricant might be the best way to go on the bendix --- oils and grease attract dirt, will gum it up. Lots of products available today that dry and provide great lubrication.

Yes -- with 6 volt systems - we used to jump start them by putting ground one cable from the "hot" (battery/starter) then on cable to the "cold" side of the battery, When you used the other end of the cold side against the machine, you completed the circuit. By not going directly to the "starter" post making the connection, you greatly reduce the ARC that will really mess up the threads on the starter post. (going directly to the starter post/ground method eliminates the rest of the components of the electrical system)

CTS

I had problem with my old GMC truck that may help - was running 6V solenoid starter on 12V, only engaged about 1/2 the time. The starter was spinning before the gear engaged - I solved it by replacing starter with a 6V "stomp start" that didn't have a solenoid.

Check the starter end plate (commutator end) for wear from the armature shaft. Those early starters did not have a bushing and were known to wear down the housing bore to where the armature would drag on the field coil shoes.