Hi Neil
The attached photo shows what it should look like so the previous owner has made a slight modification to the drip feed adjustment wheel. Basically I adjust the drip feed so I have one drip a second which can be seen through the site glass. The lubrication is just a gravity feed from the tank to the drip feed then through a "spray" bar (copper tube with some holes) to drip oil on to the crankshaft, where is is then thrown around the engine. There is scavenge pump which then returns excess oil from the sump back to the oil tank. When you have the engine running remove the oil cap and you can see the oil return pipe to make sure it is returning oil. When changing the oil don't over fill it to start with. Let the engine run and then top up the oil so it is about 1/2 inch below the top of the oil return pipe. I over filled mine the first time and oil spilled out all over the tank. Made a right mess. Hope this helps
Roy
