The visitors opened the scoring in the 16th minute when Daniel Nardiello skipped past Steve Elliott and squared to Clive Platt, who tapped in from close range.
But their lead lasted for less than two minutes, with Vincent racing onto Jamie Cureton's pass and beating Brian Jensen with a shot inside the bottom right corner.
Troy Brown nearly touched in a free-kick from Matt Richards in the 26th minute, but it was an even opening 45 minutes and it remained 1-1 at the break.
Scott Brown denied Danny Mayor with a low save in the 50th minute before Brian Jensen was called up to beat away Sam Deering's long-range strike two minutes later.
Nardiello beat Troy Brown, but with only Scott Brown to beat he fired wide of the far post in the 57th minute.
Jensen made a fine reaction stop to keep out Harrison's header after a cross from Michael Ihiekwe in the 66th minute, but he was beaten with eight minutes left as Jermaine McGlashan's fine run and cross on the right was touched in by Harrison for his 12th of the season.