tinker, repair, replace, devise, overhaul, fix, refit, piece together, improvise, adjust, patch, invent, concoct, salvage, correct, rig up, rejigger, fiddle, cobble together, remove (an obstruction), maintain, service, rebuild, mend, mess around with, restore, refurbish, recondition

figure out, mold, fix, rescue, strategize, guess, modify, alter, anticipate, redo, piece together, invent, finesse, persuade, concoct, juggle, puzzle out, work out, get to the bottom of, come up with, put (heads together), hit upon (a solution), turn (something around), turn to, think something through, rethink, figure in, debate, reason, salvage, correct, extemporize, justify, hatch (a plan), substantiate, predict (outcomes), foresee (potential consequences), calculate, shape (a plan), straighten out, comb through