Here are your parts
Replacement parts for lnc7766a71 models | AppliancePartsPros.comI do not have a wiring diagram for the unit so the below is a bit of a guess.
It sounds like a timer problem.
I am assuming the timer rotates past off to the next cycle.
Unplug the nit and open up the console.
The timer should have connections marked L and M.
L is power in (L1).
M is for the motor.
Remove the wire going to one of these. This prevents you from reading an alternate/parallel circuit path.
Now measure across the 2 connections.
When in a cycle, they should read 0 ohms (closed).
When at off,they should read infinity (open).
If they do not open then the timer is toast, the contacts are welded together.
If you do not own a meter, I would suggest you purchase a one. You can get a decent digital multimeter for under $20.00. You do not need fancy though it is nice if the leads are a couple feet long.
If it saves ordering one unnecessary part it has paid for itself and you end up owning a useful tool.
Most places will not let you return electrical parts so if you order it, you own it.
A couple things to watch when measuring ohms and continuity
1. Always remove power from the machine otherwise you could blow your meter.
2. Always disconnect at least one side of any device you are checking. This eliminates the possibility of measuring an alternate/parallel circuit path.
3. When checking for closed contacts and continuity use the lowest scale (Usually 200 ohms). Then try higher scales. This scale is 0 to 200 ohms so if the device you are measuring is 300 ohms this scale would show an open circuit which it is not, you are just measuring outside the scale's dynamic range.
There is a good STICKY at the start of this forum about it's use.
Note: You may find the wiring diagram in the console, it is a favorite storage area for many manufacturers.