I think it depends on the situation.Many of those old Broadwoods have actual machine threads on the tuning pins, which thread through the plate into the block below. With this kind of an arrangement, I would be extremely careful with CA (meaning I would not do it). You do not want the pins to become glued into the plate. Remember: first, do no harm.
Some old pianos can not be kept limping along anymore with band-aid solutions- they need wholesale work to be rendered into a playing condition. If the funds are not available at this time, they may have to remain non-tune-able, non-playable artifacts until the day that the owners decide to make the plunge.