Aha, the only way I can get this pattern to work is to change the number of sts in the odd number rows. I assumed that the centered double decreases (the sl1, k2tog, PSSO) should line up. Keep them aligned to stay on track with the pattern and count sts every row. I also worked the double yarn over as a purl the first yo, purl through the back loop into the 2nd yo.
Then here is the modified pattern:
Cast on 50 stitches and work 3 rows on garter stitch (every row knit)
1st row:-- K1*yarn forward Knit 2 Slip 1. Knit 2 together PSSO Knit 2 Yarn Forward Repeat from * to end Don't forget the final yf. You can thumb cast on a stitch here if you like.
2nd row :--Purl (purl first yo, ptbl 2nd yo)
3rd row :-- Knit 2 * YF,K1, SL1.K 2 tog PSSO K1 YF K2 Repeat from* to last 6 sts YF,K1, SL1,K2 tog PSSO K1 YF, K1
4th row :-- Purl
5th row:-- K3* YF,SL1.K2 tog PSSO, yf, k4 Repeat from * to the last 5 stitches YF, SL1,K2tog,PSSO.YF,K2
6th row:-- Purl
I'll post a photo of the test knit done on 22sts (3 repeats of 7sts plus one stitch). I repeated the above rows twice. .