Bridge Of Years by Robert Charles Wilson
Tom, a middle-aged guy in 1989, retreats to a farmhouse in Washington state after a hurtful divorce. Lo and behold, the house is filled with cybernetic “machine bugs” who have been trying to rebuild their dead human master ten years after a marauder from the future killed him in that very house (detailed in a vivid prolog).
The bugs try to communicate with Tom through his television set, soliciting his help. Their master was the custodian of a time-machine tunnel in the basement. Instead of investigating this deeply fascinating situation, Tom ignores the machine-bugs and trots off down the tunnel which has been damaged by the marauder in his escape to the past and now only opens onto Greenwich Village in 1962. Tom thinks that’s so groovy that he wants to stay there forever.
Luckily a real estate agent and a neighbor end up helping the machine-bugs revive their master. The three of them go into the past to rescue unsuspecting Tom (who’s fallen for a cute beatnik) from the paranoid marauder. A fun read with some amazing scenes of the marauder’s time period: a chaotic, war-torn futuristic United States.