Eyeing a 1999 PS-1 MTH Doodlebug: how do I check for the "three clanks?"

I'm eyeing a 1999 MTH PS-1 Doodlebug in a resale shop that sells many varied items & only a few trains.  Assuming the owner lets me test it before buying (I would bring an MTH transformer &  attached track section), what do I look/listen for to see if it has the dreaded battery death issue?  I've read the numerous posts here about the "three clanks of death"/chip replacement & BCRs & frankly my head is spinning!  Is this a can of worms not worth opening?  Thank you!