I cant seem to get the bump knob off to change the line can you help?

I would recommend using something a bit more hefty like self adjusting locking pliers or even a plumbers' pipe wrench. If you can get the bump feed to free up, but it's out of trimmer line you may be able to manual spool it. Found a how-to vid on youtube that may be relevant to your model Ryobi trimmer -
Howto string Ryobi trimmer

Use Channel Lock Pliers to unscrew the bump knob CCW depending on what model Ryobi you have.

I'll send you a link to the operators manual. To change the cable, simply unscrew the bump feed knob anti-clockwise.

hello, To keep the shaft or trimmer head from turning when trying to remove the bump knob or blade insert a screwdriver in the slot on the other side of the head and remove bump knob or blade,hope this helps,,

hello, To keep the shaft or trimmer head from turning when trying to remove the bump knob or blade insert a screwdriver in the slot on the other side of the head and remove bump knob or blade,hope this helps,~~

SOunds like the emulated line out is the problem IT may be defective. Is this a button or a knob? It may have dirty contacts and MIGHT be able to be cleaned with electronic contact cleaner.

As a general rule it is right hand threads on curved shaft trimmers and left hand threads on straight shaft trimmers. The major exception is on homelite manufactured units. On Homelite units the black bump knob is right hand and the red bump knob is left hand

Grasp the outer portion of the cutting head in your left hand and turn the inner knob with your right. Depending on model, some bump knobs are threaded and some are post and notch. Use a little spray like wd40 to loosen the mechanism. It may take a firm hand, but the two will separate so that you can reload the line. Consider reloading with the .095 five sided line. It cuts much easier than the round line.

Unscrew the bump-knob and the rest pulls off. If it won't unscrew you could always cut it off and buy a new one from ALM Manufacturing 01423 797208