Possible Clues:

• Could you be making a hole with anything so dull?
• Bit required for this routine
• Drilling - it's monotonous
• Dull and repetitive, a turn-off
• Making holes is tedious
• It's 23 down on the whole, by the sound of it
• It¿s not very interesting to rob back gin cocktail
• Dull king captivated by sound of spring
• Drilling
• Pedestrian operating drill