Straight Beam Guns, Ion Trap?

[RitchieMars]

My rebuilt 17LP4 arrived this week. It's an old rebuilt tube that was never used after rebuild. I believe it was likely rebuilt around 1970. The odd thing is that this tube calls for a bent gun and the use of a ion trap whereas this one was rebuilt using a straight gun. It appears that bent guns were becoming hard to come by during that time. What I'm wondering is this: Since the tube doesn't appear to be aluminized, wouldn't that mean there's a good chance that the straight gun will eventually create some ion burn on the phosphor screen?

If so, is there a way I can avoid this? It's been suggested to me that using a pair of ion traps might work by positioning the first to bend the beam to scatter the ions, and the next to bend the beam back into place. I only have one and it's the standard one that came with my Zenith's original 17LP4.