Lee Sinnott's men looked set to celebrate a rare victory when Ricketts rose to head in a cross from former Vale full-back Rhys Weston in the 90th minute.
Marc Laird, on loan from Manchester City, gave the home fans some much needed festive cheer with his first goal in the Football League in the 12th minute.
Dave McGoldrick found him with a crossfield pass and Laird cracked an unstoppable 25-yard shot which flashed low inside Clayton Ince's right-hand post.
Walsall were dealt another blow four minutes later when top scorer Tommy Mooney limped off to be replaced by Edrissa Sonko.
And the confidence was now flowing from Vale as Paul Harsley's shot was deflected for a corner, then a George Pilkington header was clutched by Ince.
The visitors offered nothing until the 32nd minute when Ricketts should have levelled when he headed too high from Peter Sweeney's inch-perfect cross.
Vale were then forced to make two quick substitutions with scorer Laird and left-back Jason Talbot taking knocks and being replaced by Robin Hulbert and Colin Miles.
And Miles himself was stretchered off after a strong and fair challenge by former Vale full-back Weston on the stroke of half-time.
Walsall still got no joy in the opening stages of the second half, however, and manager Richard Money replaced the ineffective Troy Deeney with Ishmael Demontagnac in the 55th minute.
But Vale refused to lie down and Luke Rodgers could have made their task easier when he snatched a clear opportunity too high just past the hour.
That task eventually should have become easier after Walsall full-back Daniel Fox was sent off for his second booking, a trip on Callum Willock, in the 68th minute.
But Walsall kept going and Ricketts' goal sent Vale to the bottom of the table.