BX starter getting weak

The starter on my BX2230 has been getting progressively weaker. A couple of times it wouldn't crank at first and after trying it several times got it to crank and start the engine. Now, when I turn the key to the start position, noting happens for a seconds or so, then it starts cranking but slowly. So far it cranks fast enough to start the engine, but I'm not going to wait until it fails completely.

Has anyone had any luck with local rebuilders repairing these Denso starters?
If so, I would like to try that before I shell out over $400 for a Kubota starter.

There are aftermarket starters on Amazon for around $100. has anyone tried one of those?

And no, it's not the battery, cables or connections, I have checked all those and they are good.

Henro said:

Sounds like the brushes in the starter motor have worn short.

Perhaps you should check/replace them...

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That's kind of what I was thinking. I'll pull it off and take a look at it this afternoon and report back,

Thanks.

So, I took the starter off, pretty easy after you remove the engine cowl. First thing I checked was the solenoid contactor, and while the contact plate looked pretty good, and I have seen some with holes burned completely through, there was a little tit of copper on the contact that goes to the starter motor. You can see quite plainly in the third picture. That would definitely would be a high resistance point with all the current going through it. I cleaned up the contact plate, scraped the little piece of copper off the motor contact and cleaned up both contacts so they will make better contact.

I pulled the end cover off the motor and the brushes look pretty good, probably 3/8" long or so, the brush holder doesn't look like it had been hot, and the armature looks fine also
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I put the starter back together and put it back on the tractor, and now it does turn the engine over faster that it did before. It doesn't hesitate before it starts cranking like it did before.

We'll see if my fix lasts, or if I need to pull it I may put in new brushes and have the armature cleaned up. Looking at the parts manual, it doesn't appear that the brushes are sold separately, but you have the buy the complete brush holder assembly which is over $40 at Messicks. For another $45 I can buy an entire starter on Amazon.

I'm certainly not going to buy a $400 starter from Kubota.

SDT said:

Are you CERTAIN that it's not the battery or cables?

If so, you can buy aftermarket starters on line. I bought a new starter/solenoid assembly for my B1750 for $72.00 delivered about a month ago.

SDT

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Yep, I pulled the battery and put in a new one I had on hand for my Chevy Nova, and it didn't crank any faster. I also took both the hot and ground cables off on both ends, cleaned them and reinstalled them. No difference.
Kinda leaves the starter as the culprit.

Took the starter off this morning and took it to an Amish shop that does a lot of lawn, garden and farm equipment starters, generators and alternators. He pulled it apart and when he checked the armature, he found it was shorted or open on one of the windings. He does a lot of Kubota work and had a rebuilt one on the shelf. He also said the Denso starters are usually pretty good, but every now and then he gets a bad one, usually from someone cranking the engine for a long time, like if the glow plugs aren't working. I guess it's a common starter on a lot of small equipment.

Paid $75 for the rebuilt unit with a 2 year warranty.

Took it back and installed it, and holy cow, it has never cranked that fast before! I always thought it cranked little slow, but it always started.

So, mystery is finally solved.

Thanks for all the suggestions.