oil dipstick tube removal

Hey all. I have a '86 Cavalier with the 2.0 4 cylinder engine. A couple weeks ago the engine suffered a rod bearing failure. I ordered a reman sort block for it. I'm tearing the old appart to use as the core. I can't get the oil dipstick tube to come out of the engine block. I'm afraid that the more I mess with it, I'm going to break it off which would not be good. Can anyone help me with this little problem???