no start 5k

[William M. Lockwood-III]

My step dad bought a 5ktq 86 recently and has been driving it for a few
days.  He bought a new battery for it.  And after it ran "fine" (this is
definately a type 44-ism, meaning: despite other unrelated problems.) all
weekend.  He went to start it on Monday and it buzzed and clicked, but the
starter didn't turn the car over.  Other than the battery being low, what
else could be the problem?  It was raining. 

TIA
BILL