What a Service Visit Covers
Service Is Not Inspection
A visit that consists of cycling the gate twice and pronouncing it fine is an inspection, and a shallow one. A service is a defined list of adjustments and measurements, most of which are invisible to the owner, and it is reasonable to ask for that list before booking.
The Mechanical Half
Hinges or rollers are checked for play and greased. Fixings are checked for tightness, particularly at the hinge brackets and the post plates, because vibration works them loose over a season. The leaf is checked for square and its clearance measured at the stop. Any track is swept and inspected for scoring. On a cantilever gate the guide rollers at the top are checked, since they take the wind load and are the ones nobody looks at.
The Electrical Half
Force settings are measured rather than eyeballed, and the reversing behaviour is tested with an obstruction. Photo eyes are cleaned and their alignment confirmed. The backup battery is load tested, not just observed to be present. Terminals in the control box are checked for corrosion, which in humid air is the most common cause of an intermittent fault that nobody can reproduce.
The Adjustments That Matter Most
Two settings drift and cause most of the trouble: the closing force and the limit positions. Force creeps upward over years as somebody responds to nuisance reversals. Limits creep as the mechanical stops wear, so the gate begins to slam or to stop short of the latch. Resetting both to where they belong is often the whole reason a gate feels new again after a service.
How Often
Once a year suits a residential entrance with a handful of cycles a day. A gate on a busy driveway, or one on an exposed lot where wind loads it hard, is better served twice. Anything that has just had structural work done should be serviced afterwards regardless of schedule, because rehanging a leaf changes every setting the operator was calibrated against.
What You Should Get on Paper
A record of what was measured, not only what was done. Force readings, battery condition and clearance figures are worth having because next year's numbers are only meaningful against this year's. A service report that says the gate was checked and is working tells you nothing you did not already know.