I lost an m7 set screw. What do I do?

Check out McMaster-Carr.

https://www.mcmaster.com/set-screws

You’re in way over your head. Get a professional installer so you don’t end up with an electrical fire 🔥. 

If the space around the bolt is fine, then the bolt should be good until you find a proper M7 set screw.

The advice is to make the bolt the ground lug one, meaning if the missing set screw is on the power or speakers, move the set screw of same size from the ground over to the other terminal, and then use the M7 bolt for the ground wire tightening.

That way, if the ground 'bolt' is accidentally grounded to the chassis of the car or the amp, or whatnot, it does not matter...no current will flow as it is already at ground potential.

Again, if they are all m7 connections, make the ground connection the one with the bolt. You'll be fine that way until you get to finding a proper M7 set screw.

My local Ace Hardware has metric set screws.

Thanks for the advice! I ordered a good kit for this amp. The only thing missing was that one set screw. When I wire it this week, ill use the bold (unless I can find a new m7 set screw) to the ground terminal.

Its a jbl BP1200.1 mono amp (for car audio). I feel confident in my skills here, just wanted to get some extra input.
Thanks

Worst case scenario, would be to cut the bolt you have to the proper length and cut a slot in one end that would allow a screwdriver tip to fit. Do you have a Dremel tool? That would make life easier.

I found metric screws (especially set screws) at the "big box" stores are located in the hardware department in the "specialty" drawers. Just ask someone for what you’re looking for.

That's a really good idea. I thought about cutting the bolt. Ill see if my old dremel is in the garage. 

And ill keep my feelets out for an original in the mean time

(Fyi bdp24, my ace has metric too. But the m7 set screw is "antiquated" says the ace rep)
Thanks to all for responding.

I made my own m7 screws. I took Theo's advice, and I cut the hex heads off of some m7 bolts.  I put each screw in a power drill, then used my hack saw to get through each screw. 10 minute job.
Next step it to cut some flat head slots, and file off the one bur on each screw.

Thanks Theo.

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Glad to help. Have a Merry Christmas 

Once again I'll point to McMaster-Carr. See my link above. Pretty much every kind of set screw. You should be able to get precisely what you need. No rigging, no fab work.  Their shipping is often alarmingly fast. Ordered a couple of trinkets from them one night, paid regular shipping, it was on my porch at noon the next day.

Thanks for recommending McMaster, they have every set screw imaginable... Except for m7. The ones I made are perfect. Quarter inch, with a flat head top. If I could post pics on this forum, I would show you what I did. I made a few (just in case I lose another one). I'm all set. Installing the rest of the wiring this afternoon.

I'm amazed they didn't have the m7. But, if you are the DIY type (and I am) there is nothing better than solving the problem yourself.