I recently bought a second hand R8050 Di2 front derailleur as part of my slow migration to going Di2. However, having got all the bits together and started building up I noticed that the H-limit screw is been completely rounded, and can't turn it all all. I've looked for this part, and most everywhere is showing them as not in stock. I'm wondering though, if any of the other limit screws from shimano would work for these, as they're listed as M4 x 8 which is the same as the 'official'. They all look the same to me. Can anyone shed any light on this, and can I pop into a hardware store and get a bag of these type of bolt or a link to where I can purchased them.
Any M4x8mm screw will work. I prefer using an allen head in these cases. The head on an allen head is less likely to be stripped than a phillips head. Apply some Anti-Seize or grease to the threads to help eliminate corrosion. The screw should be available at a local hardware or big box home improvement center. Your local hardwarestore will likely sell you a single screw. These are small screws so get two "one to use and one to lose", just in case you drop it.