From time to time we're asked to copy a tape that will not play very well, or we just cannot get to play. And there's, occasionally, the converse (that someone has trouble playing one of our tapes). This page has information about that, as well as being a disclaimer that there are going to be some videotape issues that are simply out of our control.
From one machine to another there are mechanical and electrical variations, they're not all the same as each other. In some cases you can adjust a “tracking” control to make a tape play (these days, that adjustment tends to be automatic), but in other cases there's almost nothing that you can do about it. There's very little that can be done to play back stretched, worn out, or chewed tapes. It's hard enough to get bad tapes to play, it's even harder to make copies of them.
The VHS/S-VHS video recorders that I use are very expensive professional videotape editing machines, that are designed to be as close as possible to the official specifications for VHS and S-VHS. This means that anything recorded on them should play on any other VCR, but still mayn't if that other VCR is seriously out of specification—there's nothing that we can do about that, you'd need to get your machine fixed or replaced (you'd have similar problems playing back tapes recorded by other people, but then you'd, probably, already be used to that).
On the other side of the coin, these machines are very good at playing back tapes that are recorded within specification, and have some leeway for compensating for out-of-spec tapes. But really bad tapes will play badly, some will only play on the same machine that recorded them, and copies can be quite awful.
My edit VCRs do not play LP (long play) recorded tapes, at all, we have to use an ordinary domestic VCR to play them. They don't play back too well, and the copies will look bad, too. Furthermore, many LP recordings will only play on the machine that originally recorded them, and can get really bad over time (as they stretch and/or wear out). Don't use LP for anything that you might want to keep.
Also, any miniature camcorder tapes will have to be played back through a domestic camcorder (which tend to be designed more for recording than playback, so they don't always playback brilliantly), we don't have dedicated players for them. There's too many different types of minature tapes for us to have equipment that plays them all, and some formats will need to be played back using the customer's own equipment. At this time, the only miniature format that I can play back are the original Video-8 tapes. See the supported media page for list of different types of media, and pictures that can help identify some of them.
We receive some tapes in really dirty, crinkled, or chewed-up, conditions, such tapes will be rejected. We won't put tapes through our equipment if there's a risk that they'll damage it, or get stuck in them. Tapes that are otherwise okay, but with an outer shell that's damaged, broken, or filthy can be transferred into another shell. Likewise, tapes that have snapped can have the second part placed into a new shell, giving you a “part one” and “part two” set of tapes. Such repair jobs will be charged for the time (probably half an hour's work) and parts involved (the cost of a new video tape).