On 01/05/2021 07:13 pm, AJH wrote:

I had a mishap this week whenÂ* the main terminal on a tractor starter
motor became loose and rotated allowing it to contact the motor winding
terminal, while the engine was running. IÂ* didn't notice anything until
the damage was done.

As this is an old ford industrial engine the starter is going to take a
while to arrive so I thought I'd see if the old one could be made
functional again.

The armature seems okay, no shorts to the iron core and the commutator
and brushes are serviceable.

One of the 4 stator coils has shorted and burned off its wrappings, the
others seem fine, the copper is so large a cross sectionÂ* it is not
possible to discriminate the resistance as it is so low but the copper
rectangular section looks sound.

Now looking on you tube if anyone has the time to watch some old school
workmanship:

https://www.youtube.com/watch?v=4bFou5VIFzM

at 2 minutes the guy is cutting some insulation sheet, anyone any idea
what it is and if it is avalable?

Not seen that before (unless, as suggested by another poster, it's PVC).

We used to use Kraft sp? for layered insulation.

For example:

https://www.rajapack.co.uk/protective-packaging/paper-packaging/crepe-kraft-paper-75mmx15m-pack-of-24_skuPCKP.html?priceVAT=true&cq_src=google_ads&cq _cmp=9232197084&cq_con=101859384198&cq_term=&cq_me d=pla&cq_plac=&cq_net=g&cq_pos=&cq_plt=gp&gclid=Cj 0KCQjw-LOEBhDCARIsABrC0TnlShh9oXdT4adQ_Ihtm8l-vm_ppIwztVnvGjqlErZd6V8HO5miMXAaAvOTEALw_wcB&gclsr c=aw.ds

Later at 4:20 he wraps with a tape, any ideas what it is and where I can
get some?

That looks like a woven insulation tape, a bit like this:

https://www.mbfg.co.uk/QL5028.html?gclid=Cj0KCQjw-LOEBhDCARIsABrC0Tkl_UzPAE46ZSVhMtNtyKUOFIEgNg2Mr1x wsk1EiMzvJUwq9QK_H5QaAvOAEALw_wcB

[But completely wrapping stator coils was not common in the armature
winding world.]

At 5:40 a paint is used to cover the wrapped coil, is this likely to be
anything special?

I can see the bright colour, but suggest that that is a varnish rather
than a paint. The purpose (maybe among others) will be to hold the coil
turns firmly and prevent abrasion of the wire's own insulation by
reducing vibration "chatter".