tinker with

Try to repair, work aimlessly or unskillfully with, as in He tinkered with the engine all day but it still wouldn't start. This idiom, first recorded in 1658, alludes to working as a tinker, that is, mending metal utensils.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.