Tips for radial wheel truing Several drive side spokes on a mountain bike rear were damaged the rear mech being pushed into the wheel by a rock, with one snapping completely. I've replaced the affected spokes and have managed to get the wheel (almost) perfectly true laterally. 

However, I've noticed that the wheel is out of true radially -- i.e. it has high or low points of 2-3mm in a couple of places. I don't know if this was present before I replaced the spokes or not, but I'd like to improve this before putting the wheel back on the bike.

I think I need to tighten (or loosen) spokes equally on both sides at the high (or low) points to resolve this. But doing so seems to have little or no effect when making the kind of 1/4 or 1/2 turn adjustments I used to true the wheel laterally.

Am I going about this in the wrong way? Or do I need to make much bigger changes to spoke tension to affect the radial profile of the rim?
It's (a lot) harder to achieve in-out motion than side-to-side, and generally requires (much) more that 1/2 turn adjustments.  Plus you must usually loosen spokes on either side (2-4 spokes away) of a high spot, or tighten spoken on either side of a low spot.  For low spots sometimes you need to tighten ALL the spokes except those over the spot.

But at some point you need to either scrap the rim or employ a tool to bend the rim.  Bending out low spots can be effectively handled with a jury-rigged tool consisting of a couple of blocks of wood with holes drilled in them and a piece of "all thread" with a couple of nuts and washers.  (I've never dealt with high spots serious enough to require the opposite tool.)