Paul. I would say that it depends how grubby it is! . Some switch cleaner for the brushes and commutator (is that the correct name?) would be best as these only need to be clean, and the only thing that needs lubrication are the bearings, a drop of oil. So, I say NO to WD40 but in all probability it may not actually harm the motor. These 540 types are fairly inexpensive to simply change out, but there are different types of 540…fast, slow, low drain and so on.

What application is this motor for?

Ashley

Applying anything with oil in it to a carbon brush usually results in the brush breaking down and clogging the commutator sooner or later, effectively bringing forward the replacement day. Motors with metal brushes can be lubed in that area, but if they have got to the point where they need cleaning, they have generally reached the end of their useful life. If it is the type of motor where the brushes can be replaced, remove them first before cleaning.

The commutator can usually be cleaned using a cotton bud through the cooling holes to the point where you can see if there is any scoring or burning on it. If there is, it is time to mend it with a new one.

The only bits that need any oil are the bearings, and no more than a drop each.

Motors are generally sealed for life modules that are replaceable rather than repairable.

Check the current draw on each motor with the shafts connected to see if they are all the same as they should be.

If you have a pulley system then it might be worth disconnecting the motors and measuring the no load current draw on each one to see if there are any differences. This would indicate a motor problem.

However I rather suspect that you will find that there is increased friction in the affected shaft which may be binding slightly for some reason so that is the most obvious place to look.

Also, If it is feasible you could try swapping the two outer shafts over to see if this makes a difference. This could indicate whether it is the shaft or the tube which is binding.

A process of elimination really but rather time consuming and sometimes frustrating!

Colin

The drop of oil on the motor bearings really is the simplest first option – anything inside the motor less so.

Testing the motors unloaded is good – you have to bear in mind that motors for the model trade are rarely made to laboratory standards and one might have a marginally weaker magnet that its mate quite apart from any mechanical wear and tear issues.

Although it is nice to think that any particular problem might have a single solution as envisaged by the people who write faulting flowcharts, there is nothing in real life to say that more than one fault cannot be present at any one time.

HI paul, could it just be the shaft needs some oil? or that shaft might be corroded slightly and just needs cleaning

Mark