First time poster here, and this might be an incredibly basic question, but I hope someone can help (without laughing too much!) In the last 4-5 days the hot water tap in my kitchen has become incredibly stiff, in the last day or so it has been a real battle to turn on and off at all. The cold water tap doesn't seem to be any different than usual. Nothing out of the ordinary has happened to my knowledge, it's just suddenly got stuck. I have no technical knowledge to explain things properly, but it is a mixer tap with the giraffe neck spout and usual round taps on either side at the base. I'm really not sure how old it is, but definitely more than 3 years, probably not more than 10. Any ideas on how to fix it? It seems way too trivial to call a plumber out for, but I don't know what it needs? Oil? A large wrench? thanks in advance.