Odd alignment issue

[bobschneider]

Last night I finally finished recapping and aligning my Otari MX5050 Mk3.  So after listening to the Dave Alvin TP tape I recently received (which sounded great), I decided to try the 7 1/2 ips Ampex copy of Sgt Pepper I bought on eBay a few months ago.  For the first couple of minutes on side 1, the tape kept popping in and out of the slot in the right side guide arm.  It was also wavering back and forth between the capstan and pinch roller.  This didn't seem to affect the sound too much (the tape stayed put in the guides in the headblock), and it stopped after a couple of minutes, but it does concern me.  I tried different take up reels, and rewinding the tape on the Otari to get a better tape pack, but it's still doing this.

Is this something I should be concerned about, and is there anything I can do to stop this?  The Otari's guide arms don't appear to be adjustable (and I replaced the soft stock Otari arms with hard stainless steel aftermarket arms), and I haven't encountered this with any other tapes, so I suspect it has something to do with the Sgt Pepper tape.

Thanks!

[ironbut]

It sounds more like a tape problem then a machine problem. The first guess would be that the tape is cupped or curled. If you lay a foot or so of the tape ,oxide down on a flat surface, does it lay flat or are the edges touching without the very center of the tape laying flat and touching the surface it's on? while it's laying there, look at it from above and see if it's going in a straight line. If it's the tape, there isn't much you can do. I could also be a tape that's very worn on the edges from being played on a poorly adjusted machine/s.
The things that be doing this on the machine is adjustment of the tape guides. Most of the guides should be adjustable. Ideally, a perfect tape should flow though all the guides without touching any of the guide edges (the guide part of the guide). I keep one tape that I only use for final adjustments in the tape path. Once I've used it 5 or 6 times, I switch to a newer one. Of course, slitting errors on brand new tapes aren't unheard of so just because a tape is new, it doesn't mean that it's edges are perfectly perpendicular ( but it's pretty likely that it's very close).