Most of the machines that come into the workshop have a lot of water in the fuel, woodchip, sawdust bits of old rubber and other contaminants. Its worth dumping your fuel tank into a clean plastic jug, they only cost a pound or two from the supermarket and checking it out. It should be clear, now it may be blue red, yellow etc depending on the colour of your two stroke oil but it shouldn't be cloudy, if it is its got water in it. Let it settle and you will see a bubble of water at the bottom, you can just pour off the decent fuel and bin the dirty fuel. Pour the clean fuel back into the tank, swill it about and dump it into the jug again. Do this a couple of times to clean the tank out. Make sure you do this with the fuel can, jerry can that you store your fuel in when its getting time to refill it.

I have seen machines that have around 15-20% of water in the fuel tank, its a lot more common now with the increase of ethanol in pump fuel. Using super unleaded helps solve the issue but its still worth doing from time to time.

Ive seen plenty of fairly new hand helds with holes in the pump diaphragm, its the thin plastic thing in the carb that looks like this

If your machine is pouring fuel into the engine or the primer pump isnt drawing fuel through then it may have a hole in it.

Another thing to check is the oil tank breather vent, usually under a metal plate on the huskys and hidden behind the plastic guide rail on stihls. Differnt place son echos but usually underneath the starter cover. They let air in but stop oil coming out. If they block up it will create a vacuum in the oil tank and result in no oil to the bar.

IMO most oiling issues are caused by a worn drive or in the case with Stihls a worn or damaged worm driver, if you want to call it that. Its the metal piece that connects the worm to the clutch drum pictured here

Also dont forget to clean the oil hole out in the bar. If your chain isnt getting the right amount of oil it will cause plenty of cutting problems.

Last thought on this, oil pumps rarely fail, if you have tried the above and nothing helps and your oil pump has an adjuster try turning the adjuster back and forth as they can stick. Oil pumps are usually pricey, some not far off the £100 mark!

Im going to use this sub forum to post a few tips I've learnt over the years to hopefully help others look after their machines correctly and efficiently.

Some topics will be machine specific and others just general advice. I would  appreciate it if others could add to the discussion and also point out things ive missed, not explained correctly or maybe that there is a better way of doing things than my way etc.