Like others, I have had pretty good operation of my unit for the last several years. I have been using this cell for over 3 years now, maintaining a FC level of approx 5 throughout the usage time. However, I have noticed lower FC levels recently, wondering if the cell is near end of life. It still can produce chlorine- bubbles obviously generated when I hit 24 hr boost.

I've done some preliminary troubleshooting:

Cell is clean, evidence of wear on the outer plates
Salt level =3800, calibrated
water Temp = 80 degrees

water chemistry unchanged, parameters all ok except lower FC levels than normal FC now around 1.0 instead of the normal 5.
after hitting boost, then test pool pilot, i get the following info:
Amp hours =9120
Voltage = 28

time to replace cell?
Amps =6.5

Your amp-hours are approaching 10,000 so it's probably getting close to time for a replacement.
Have you done an OCLT (overnight chlorine loss test) just to make sure something isn't in there?

Also, it'd be nice to see a full set of test results.

That is an amp-hour reading, not an hour reading. The cell is rated for about 10,000 hours at 5 to 8 amps, so cell lifetime is typically somewhere around 50,000 to 80,000 amp-hours. Remember that actual cell lifetime is somewhat variable from unit to unit.

You need both amps and volts, read after the cell has been on for a couple of minutes, to judge if the cell might be getting old. Towards the end of the cell lifetime, the chlorine production will fall for a while before the cell fails.

Reduced FC levels are almost always caused by some chemical imbalance, not a cell problem. You should post a full set of water test results.