It looks pretty good to me (Said the idiot that totally trashed a hairspring doing a VERY SIMPLE JOB yesterday).
My suggestion would be to look elsewhere for the low amplitude issues BEFORE you even consider touching the HS. Mainspring, train freedom, dirt, pivots, etc. HS work is difficult at best.
An excellent book to look out for that goes into great detail on the repair and restoration of carriage clocks is "The Carriage Clock: A Repair and Restoration Manual" by Laurie Penman it is a comprehensive book on the subject and can be picked up quite cheap on Ebay.
Well it looks like the Winner is a winner, or at least well within spec. The Chinese standard movement is generally listed as +/-30 sec per day, although it is available with different performance specs.
The worst I get is -25 (crown left), although it does take a little while to settle down when changing positions. With a little tweaking, we could get those numbers to around +/- 10 sec per day, but I'm going to stick with this. Not too shabby for what it is.