May one clean a stain from his clothing?
Some Poskim rule it is forbidden to clean individual stains from a clothing, even though one will not launder the entire clothing in the process. Other Poskim rule it is permitted to clean an individual stain and one may even use laundry detergent or stain removal in order to clean it. If lack of cleaning the stain may cause permanent damage to the clothing, then according to all one may wash the stain. According to all it is permitted to scrub the stain off using a dry brush and the like.
 See Chol Hamoed Kehilchasa 5/33; Piskeiy Teshuvos 534/1; Shemiras Hamoed Kehilchaso 14/6
 Beir Moshe 7/33; Chol Hamoed Kehilchasa 5/33; Shemiras Hamoed Kehilchaso ibid footnote 15 in name of Chut Hashani
 The reason: As cleaning a stain has the same status as laundering an entire clothing as seen from the fact that a special allowance was needed to be given to allow the cleaning of a Kesem from a Nida.
 SSH”K 66/73; Shearim Hametzuyanim Behalacha 104 Kuntrus Achron 13; Rav SZ”A in Shulchan Shlomo 531; Rav Moshe Feinstein in Hilchos Chol Hamoed Zichron Shlomo 10; Rav Wozner, brought in Chol Hamoed Kehilchaso 5 footnote 86; Rav Elyashiv brought in Mevakshei Torah 106/48; Piskeiy Teshuvos 534/1
May one wash the stain even if it occurred before Yom Tov? Some of the above Poskim rule that only a stain which occurred during the Yom Tov may be cleaned during the Moed. [SSH”K ibid; Piskeiy Teshuvos ibid] Other Poskim rule that even a stain that occurred before Yom Tov may be cleaned. [Rav Moseh Feinstein ibid]
 The reason: As it is permitted to launder clothing which constantly get dirty, such as towels, [see Michaber 534/1] and hence the same should apply to a mere stain, which is a common occurrence for a clothing. [Poskim ibid]
 Chol Hamoed Kehilchaso ibid