The owner of this drill complained that it work perfectly one minute and then stopped the next. It was making DIY a very slow process.
As this was a cut-out problem rather than a slowing down issue, power problems were a likely suspect.
On test, the cable flex near the base of the handle seemed to be the issue as giving it a good wiggle seemed to reproduce the fault.
Opening up the drill (several self-tapping screws) revealed a fairly straightforward layout with cord, mechanical connector, smoothing circuit (mains splash) and switch. Having suspected the culprit to be cable flex near the handle, I cut the cable down and re-made the connection, removing the suspect part of the cable.
Despite cutting the cable flex down by about 8″, the owner was pleased with this fix since no spare parts were required and no real issues will be noticed since it will be mainly used with an extension lead.