The Bachmann /Mainline 204HP Class 03 has been around since the 1980s and has dropped in and out of the catalogue ever since; there must be thousands of them out there. It was pretty cutting edge technology at the time featuring a heavy split-frame chassis giving a running quality that was way in advance of any contemporary model diesel shunter. They're a pretty rugged beast and need little maintenance. This particular example is one of the early Bachmann production and was bought second hand; the jackshaft drive has been lost along the way, but this doesn't notice to much being hidden behind the rear steps. The running was getting slightly rough, so time to give it a clean and lube.
The loco is disassembled by first removing the chrome outer screws which release the couplings and body, followed by the black centre screws which release the plastic keeper plate.
The wheelset can then be lifted out as one. The U shaped axle bearings should be cleaned out with a dry tissue to clean out any grease and swarf. Then a tiny amount of plastic-friendly grease should be smeared onto the plastic gear wheels in the centre.
One of the great advantages of the split-frame block design is that at this point you can drop the entire thing onto a length of track, gently turn on the power and the motor will (or should) turn freely and spread the newly applied grease over the gear teeth. Remove any excess with the tissue.
The axle bearings should now have a tiny drop of oil such as electrolube added at the foot of each 'U'. This really should be an absolute minimum and should not be allowed to spread anywhere else.
Here the wheelsets themselves were in a bit of a state with several years worth of accumulated grease, dust and muck caked around the back of the wheels. This needs to be cleaned off, but be wary of using any spirit-based cleaning fluid in case it attacks the nylon axle muffs. Here I just used a dry tissue again. The wheel treads were also cleaned at the point.
Most of the Mainline and Bachmann locomotives contemporary with this will use a similar assembly and can be treated in the same manner.