Tape won't load.
This is a problem with the process called 'tape loading' - pulling the tape loop out of the cassette and wrapping it around the spinning video drum, engaging the capstan and pinch roller and reel rotation.
With the cover off, observe the behavior when you hit play. (You may need to put a piece of cardboard over the cassette to block external light from interfering with the start/end tape sensors). Assuming this is a basic VCR (no instant start features), you should see:
1. The video head drum begins to spin.
2. the roller guides move smoothly on the tracks, wind the tape around the drum, and stop snuggly pressed against the 'V-stopper' at the end of the tracks.
3. The pinch roller moves into position and presses the tape against the capstan.
4. The tape begins to move and is wound up by the takeup reel.
5. The picture and sound appear on the TV.
With a 'rapid or quick start' (or it may be called something else) transport, the tape moves to a half-loaded position when the cassette is inserted.
This is at an intermediate position partially pulled out of the cassette but not wrapped around the drum. On VCRs with a real-time counter and/or index search capabilities, the tape will be in contact with the control head.
With an 'instant start' transport, the tape will fully load around the spinning drum when the cassette is inserted but the capstan will not engage and no tension will be applied to the tape until you press PLAY or REC. (After about 5 minutes, the drum will stop and it may unload to the half loaded or unloaded position.)
Note that for VCRs with a real-time counter and/or index search capabilities, the tape must be in contact with the control head (but not the video heads) for all relevant modes. These VCRs (which include many modern units) must therefore pull the tape at least partly out of the cassette.
In all cases, the completion of the sequence results in approximately the same mechanical configuration during PLAY.
Several likely possibilities when it shuts down:
1. Everything occurs as above, picture and sound appear for a few seconds, but then the VCR unloads the tape, ejects the cassette, goes into REW mode, stops, or shuts off. Two common causes:
The takeup reel does not turn and tape spills into the machine. This is sensed by the microcontroller which aborts record or play and attempts to save your valuable cassette. Most likely cause: old/dirty idler tire. As a test, turn the idler tire inside-out. The fresh surface will now work well enough to confirm this diagnosis and will continue working long enough for your replacement idler tire to arrive. See the section:
"General guide to VCR cleaning and rubber parts replacement".
The takeup reel is turning properly but one of the reel
The takeup reel is turning properly but one of the reel rotation sensors or its electronics is defective. As a test, check to see if the tape counter is changing at any time during the loading and