I have a set of old Peter Hunter drones that now play in tune, a bit of change from a few months ago, but the tenor and bari like cutting out mid-tune and that’s when I get them to drone in the first place under any but the lightest of pressure. And by that, I mean less pressure than it takes to sound the chanter, which is really just a bit useless. If I have the chanter going, it’s nearly impossible to start the drones. I’ve futzed with the reeds – fiddling with the bridles and with the bit of blue tac at the end of the tongues – without much effect.
Over the years, the bores in the slides (which are some kind of blackwood or ebony) have warped, I reckon, so they’re no longer straight, but rather slightly tapered. This makes tuning them a faffy, two-handed job and I have no idea if that could effect the tuning or general behaviour of the drone, but it might be a consideration. At the very least, it’s a hassle when you have to tune them since you can’t sound the drone and slide it one-handed at the same time.