Ignition and Key problems!!!! Can anyone help?

I have a 1972 camper van with a 1600cc motor. Lately I have had a hard time getting my key to go into the ignition. Most of the time I can get it in no problem and it turns easily. But sometimes it is hard to get in but turns easily, but now I can't even get my key to go in. There is no steering lock on the car and if I look into the key hole there are 2 metal pieces that normally spread to let the key in but the won't budge. Please can anyone tell me whats going on here and/or what i need to do to fix it???

Try shooting some lubricant in the key slot , white lithium grease would be the best. if this doesn't fix things then its time for nrw lock assembly.

Mario Vintage Werks Resto.