Hey Frosty (please read "Forum Rules" and place your real name in your signature),
Larry's right.
If you plan to do much recording, you'd be much better off using one of the current production tapes such as RMGI or ATR Magnetics.
Ampex 456 is great sounding tape when it was new, but over time it is prone to sticky shed syndrome (and is actually the worst offender).
Sticky shed is what Larry is talking about.
At the very least, it will effect the high frequencies and will progress to stopping your machine dead in it's tracks.
Thorough cleaning of the entire tape path is needed after using a tape with sticky shed.
There is more info regarding this problem in "The Beginners Guide" located in a sticky (no pun intended) above the General Forum (post #24).
If you need a source for new tape, try US Recording Media.
http://usrecordingmedia.com/