The "tags" can be bent back allowing the white end cap (remove all solder with a file) to be lifted off. Note the brushes will/maybe attached or fitted to the white end cap and will need to be pushed back (very thin screw drive) as the cap is refitted.
It's a dc motor so the dc is what you need to measure. The lower ones look too low. What voltage is the motor rated at? 19v would be ok for a 12v motor but 3v seems too low. I think alot of wire feeds are 24v. If yours is then the voltage is o low.
The feed will be noisy hence the erratic at measurement. A capacitor would smooth it out a wee bitty
Clarke 151EN, gearing looks good to me, all cleaned out properly, no **** in there, no broken teeth or mis-shapen ones. the pins are good and secure too.
As mentioned it's a DC motor. If I recall they are a 24V motor. I think the slight fluctuations showing on your meter are from ware in the gearbox (hence the noise as well) You could try a new motor as you mentioned it is available but don't think it would cure it. You might find a complete welder listed as "spares or repair" on the likes of ebay that may have a good feed assembly.
Pity you don't live in the states ! see link and the ebay link in the replies as well http://weldingweb.com/showthread.php?424211-Wire-Feed-Motor-for-Clarke-100E-mk2
Similar but no........ i decided to go down the route of stripping down the gear box and feeling by touch whether there were any sticky bits. There was and on more than one cog but mostly the second. I then proceeded to clean off any burrs from each tooth and put it all back together again, it felt much smoother after this so i put back the motor and installed it all tonight.......... AAAAAAARGGHH still the ****** same. To be honest i couldn't believe it.
I took the last cog out (the one with the feed wheel) and tried the torch - same erratic feed noise, then the next, the next, the next .... still there!
Then a light bulb switched on....... its the ****** motor itself! Inspecting it i could see no damage other than what i had done by clipping wires but i then turned the small cog by hand and there it was. The tiny little stall is coming from the motor itself.
Well at least thats no 70 bucks, i can get one for a ten spot plus postage from clarke, probably cheaper on the bay.
Ill order one up (if i can find one), install and report back all fixed (he says with crossed fingers)
Had a windscreen washer motor that was rough and would only work if you spun it by hand. Took it apart just to find out why it was rough and one of the magnets had come unglued, a good clean up and a spot of Araldite fixed it as the original glue had left a witness mark on it's position.
As the motor is a permanent magnet type then as you turn the shaft you will "feel" a slight resistance as the iron core of the shaft passes the magnets. Still worth a try. (fingers crossed for you)
back to the garage and stripped the motor. couldnt see anything wrong but i see what you mean about the magnets. i have put it back together and will try a weld tomorrow night. ill upload a vid and you can see how it does sound better than before
Well, surprisingly, all the hard work seems to have paid off. It's all back together again and first welds are good. The erratic feed problem almost completely gone, i can hear it but not sure anyone else would. The weld beads themselves look good and I'm happy to start using it again.