fiddle with

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb To manipulate an object, especially in a nervous or restless manner.
• verb To adjust the position, as of an electronic device, in order to provide better reception or signal.
• verb figuratively To manipulate in order to gain something for oneself.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb manipulate, as in a nervous or unconscious manner