I work in a major school where gum or blu/white tack is a major problem on a bonded cord carpet.
I steam to soften and remove dirt from surface, scape of excess and dry off[ then apply citrus gel using a perforator.
I then scrape, use solvent on a cloth, wire brush, swear (a lot), try rid a gum on some hardenened stains, seems to work like magic on some gum patches, doesn't work on others. (watch for running off the gum and into the backing),
finally HWE with a prespray and a solvent booster in the tank.
Blu/white tack where I can recognise it before I start the above I will treat with lighter fluid.
On this particular type of carpet (or should I say flooring) I have found citra clean and the ashbys chewing gum wand to be ineffective
Hope this adds to the input
Regards
Eddie