Just had this same issue. Traced it to the combination switch and took it apart until I narrowed down the cause. Same issue as described here. I snapped a couple of pics to be helpful in case there wasn't something on MUD about this. Mine is a RHD model but same thing really, just reversed on the combination switch:
Problem area is circled in red. So the way this thing works is there's a metal pin driven down by the position of the lever. No pressure on the pin is the same as highbeams being on, ie, stalk pushed forward. Pressed in half way is low beam position. Pressed in all the way is the same as pulling the stalk towards you, to flash the lights. In the picture above, the pin has no pressure applied, and there are contacts on those two metal plates in the middle of that circle that were supposed to be conducting. They weren't, there was no electrical continuity in that position. If I tapped that top metal plate lightly, the high beams would flash.
The problem in my case was twofold. There was a little bit of buildup on the contacts, so I gave them a bit of a clean. This wasn't the main issue though, as it didn't immediately help much. The main issue was that long metal plate. It flexes when the pin moves, and the high beams rely on it applying pressure to the contact on the lower plate when the pin is fully retracted. If you leave your lights in the low beam position most of the time though, like I do and most of us probably do too, the plate is under constant tension. I believe over time this results in the plate gradually bending, so that it doesn't apply enough tension to tightly bind the contacts in the relaxed (high beam) state. In my case, I slightly bent the plate back towards the lower plate, and it started working again perfectly.
I'll probably replace this switch in my next parts order, but if you need a quick workaround or don't want to splash for a new part, I'd suggest slightly bending that plate in addition to cleaning.
Problem area is circled in red. So the way this thing works is there's a metal pin driven down by the position of the lever. No pressure on the pin is the same as highbeams being on, ie, stalk pushed forward. Pressed in half way is low beam position. Pressed in all the way is the same as pulling the stalk towards you, to flash the lights. In the picture above, the pin has no pressure applied, and there are contacts on those two metal plates in the middle of that circle that were supposed to be conducting. They weren't, there was no electrical continuity in that position. If I tapped that top metal plate lightly, the high beams would flash.
The problem in my case was twofold. There was a little bit of buildup on the contacts, so I gave them a bit of a clean. This wasn't the main issue though, as it didn't immediately help much. The main issue was that long metal plate. It flexes when the pin moves, and the high beams rely on it applying pressure to the contact on the lower plate when the pin is fully retracted. If you leave your lights in the low beam position most of the time though, like I do and most of us probably do too, the plate is under constant tension. I believe over time this results in the plate gradually bending, so that it doesn't apply enough tension to tightly bind the contacts in the relaxed (high beam) state. In my case, I slightly bent the plate back towards the lower plate, and it started working again perfectly.
I'll probably replace this switch in my next parts order, but if you need a quick workaround or don't want to splash for a new part, I'd suggest slightly bending that plate in addition to cleaning.
