Adjusting oiler on Farmi processor

[Woodworks]

Hope someone might have some bright ideas. My oiler on my processor has stoped working and I have found the fault but fixing it looks so easy in a diagram but the reality is access is a nightmare. In the picture attached the M8 nut needs tightening but the bolt is in a slot to allow adjustment of how much presure the roller exerts on the pipe and in turn to adjust how much oil gets pushed through the pipe. Now this would be OK if access was easy but it's all I can do just to get 2 spanners in there at the same time let alone the subtleties of adjusting it's position while tightening. Hoping someone has found a good way to do this as I am at my wits end this evening. I have pinged an email to Riko but need to get this sorted ASAP.

 

Thanks