I've reviewed the various Ethernet cable testing questions here and they don't address my particular issue.
I have this super cheapo tester:

I've used it successfully with Cat5e cable and one 30' or so cat6 cable. Today I made an approximately 60' cat6 cable and the tester is flashing the LED for position #5. That's it, no sequence, just that one LED. Battery is measuring 9.65v
I've looked through the "manual" but there is nothing about this. I've also read a description of the product on Amazon which is helpful (so I will include it in this question for others) but doesn't address my situation:
Following are abnormal connections:
If one cable, for example cable NO.3 is open circuited, the two NO.3 lights of the main tester and remote tester will not turn on.
If several cables are not connected, several lights will not turn on respectively. If less than two cables are connected, none of the lights is on.
If two ends of a cable is disordered, for example NO. 2and NO. 4, then displays on:
Main tester: 1-2-3-4-5-6-7-8-G
Remote tester: 1-4-3-2-5-6-7-8-G
If two cables are short circuited, neither of the corresponding lights is on of the remote tester while main tester remains unchanged. If three cables, including three, are short circuited, none of the corresponding lights is on.
If test patch panels or wall plate outlles, two cables which can match each other (RJ45) will be connected to the tester.
If test cables of the same axes, BNC turns on when the cable works.
9V reduplicated battery is used in this tester. Battery is advised to change if any weak light appears.( Battery is not included.)
Does anyone know have experience with a similar tester and know what a single flashing line indicator LED means?
Update: I've just tested it with a 80' cat5e cable here at work and it's operating fine.