Regarding the front brake master cylinder, maybe this will help?
What fails most often on master cylinders is the cup seal. One tiny and cheap elastomer part has a problem and pfft! The seal in yellow:
Cup seals push outward under their own compression, but also are forced to expand outward under braking pressure. When the lever is out, there is zero hydraulic pressure on the seal because it is upstream of the brake fluid refresh hole that connects to the reservoir. When you pull the lever in, it immediately passes over the refresh hole. The hole is really tiny, but if it is microscopically tiny bit on the sharp side, the edge of the hole can erode or even cut a smiley chunk out of the cup seal lip. The symptom of a failing cup seal from hole erosion or cutting is normal brakes most of the time, but every now and then suddenly nothing when you pull the lever in. A frantic pump or two will magically bring the brakes back until the cut gets bad enough to have the brake fail as though from the next failure mode.
Another failure mode of cup seals is degradation of the elastomer such that elastomer fails to exert natural sealing from compression in the bore. Over time, the seal relaxes back enough to not hold pressure after sitting a while because the seal hasn't been forced to expand outward for a while by hydraulic pressure.
Elastomer failure can happen if mineral (petroleum-based) oil seal compounds are exposed to the alcohol based DOT 3 & 5 and certain 5 fluid elastomers. Unsure about the other way around, DOT fluid seal elastomer compounds exposed to mineral oils.
The cure is to buy a new piston with seals kit and make sure to use the correct fluid to match the seals. Much cheaper than a whole new master cylinder. And the designs are typically simple and easy to fix. Can't say about that mongo master cylinder on the 701 as I have not had that one apart before, but it's usually a snap ring once you get past whatever seal is in front of the snap ring. Then it's just a piston with a spring behind it. Very simple to work on the things, except when manufacturers make getting past the outer sealing boot a royal pain in the ass.
A rare failure with front brake master cylinders is cylinder scoring or wear, in which case the master cylinder is toast. A failure that is uncommon on hand brake and a little more common on foot brakes because there's more dirt 'down there' and there is more side force applied to the piston on foot brakes from the activation rod.
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On another issue, tonight I removed the kickstand to weld on a larger foot (for sink-into-ground reduction). I noticed then the magnet in the tab that is for informing the ECU the kick stand is down via the infamous 'kickstand switch' has the magnet swung away from the sensor when the stand is up. So I'm like well duh, why not just remove the tab to make the switch permanently un activated?
Kickstand magnet tab attached:
The tab is probably a powder-metal part from the the ejector-pin marks. The magnet is small and in the end of the tab. It swings out of the way when the stand is up, and in front of the sensor when the stand is down. So I thought well duh, what if you just remove the tab, like this?
The proof that this works to at least get rid of the irritation of no start with kickstand down is with kickstand removed the bike starts.
In the old days the kickstand switch was indeed a simple 2-wire switch. Not any more. They are now more 'sophisticated' in communicating yes-no to the ECU. I did order a kickstand dongle, which has yet to arrive. The dongle fools the ECU into believing the 'switch' is still there and the kickstand is up. Simply. Not wasted money because if the sensor fails for whatever reason the evil thing can strand you in the boonies. So best to toss it in the bin.
And who knows what this 'mystery loop' thing on the kickstand is for?