Some years back I bought a beautiful 1975 disk-braked Guzzi Eldorado, and rode it for some years.
On the way to a Guzzi Rally it started popping and backfiring and losing power and finally wouldn't run at all, just pop and fart. A guy on a Harley lent me his phone, I called a buddy at the Rally, and they came with a trailer and got me and brought me to the rally.
I set up shop under a shelter, bike on the centerstand and my tool roll laid out, and soon I was surrounded by mechanics. Some of these guys had built racing Guzzis and they knew their stuff.
We started with the valves (Compression/Ignition/Fuel IN THAT ORDER remember) , checked compression and valve settings, all OK. Then on to the dual-point system - took out the points, cleaned them up, put them back, checked grounding and insulation, set timing and dwell and gap (we had all the right tools). I ran up to the store and got a new condenser, replaced it, still no change.
We took both carbs completely apart, reset float heights, checked internal gaskets, choke seals, accelerator pumps, put them back together, drained the tank, replaced the fuel, still no change.
By this time, 6 guys had been working on the bike for 4 hours (24 man-hours, like me spending 8 long evenings working on it) and everyone started giving up. I was sitting staring at the bike when a guy, half-jokingly, said "If you want a way to get home, I've got a running Guzzi here I'll swap you even-up for this one."
My bike was about a $5500 bike, and his modified 1000SP was about a $2500 bike, but after a few minutes of contemplation I said "Deal!" and rode his bike home (I subsequently put 30,000 miles on it).
He called the next day and said "I'm sure you don't want to hear this, but ..." and I said "YOU S.O.B.! YOU GOT IT RUNNING DIDN'T YOU?"
He said "Yep. Both your old condenser AND the new one in the box were duff. Got another new one and she's running like a sewing machine ..."
So for a $3 condenser and lack of a little patience I took a $3000 financial hit.
Don't be like me!