With a used gun god only knows what may have been done to it by a previous owner.
Here's a few things to look at.
As above, field strip and give it a good clean and fresh lubricant.
Check to see if the factory recoil spring system has been changed and remove any polymer buffer washers from the system.
Polymer recoil buffers are well known to cause failures of the slide to lock open because they limit slide movement. Since the Officer's slide has much less movement then the bigger 1911's a buffer often won't allow proper function.
The factory system was a short mainspring guide with two recoil springs.
The double springs can be replaced with a single spring that equals the strength of the double spring factory.
The factory double spring equaled 22 pounds. You can use a single 22 pound spring from Wolff Gun Springs, and up to a 24 pound spring if you shoot hot loads over 860 fps.
If the factory recoil spring system has been replaced with any kind or guide rod or replacement recoil spring plug system check to full length movement of the slide.
Check the magazine to insure it's in factory original condition.
Often follower and spring kits were installed to allow changing the 6 shot magazine to 7 shots. These may cause slide lock failures.
Remove the slide and barrel from the frame.
Check the plunger tube to insure it's seated flush against the frame, and that the tube is not loose.
Tubes that are loose or not flush on the frame will usually cause slide stop and safety problems.
Check the back side of the slide stop for a letter or number stamped on the back. Colt factory stops usually have stamps.
Insert the stop into the stripped frame and check for free movement.
Make sure the rear face of the stop has not had a dimple ground in it. These are often added to prevent the stop from prematurely engaging and often this is over done and the stop fails to operate correctly.
If you feel good with it, fully disassemble the frame.
This is not terribly difficult task, and a 1911 series owner should know how to do it. John Browning designed the 1911 to be easily and fully disassembled. The Officer's Model and guns with the Series 80 firing pin lock are only slightly more difficult.
The only "watch out" with the Series 80 firing pin lock system is to MAKE SURE the levers in the frame are properly positioned. If they aren't the firing pin will not unlock and dry firing will seriously damage the firing pin and the lock.
Full instructions for total disassembly are in the Jerry Kuhnhausen Shop Manual Volume One on the Colt .45 Automatic.
This is a training manual for new gunsmiths and shows full disassembly and gunsmithing on all the Colt 1911 pistols.
It's the best money a Colt owner can spend.
With the frame fully disassembled you can remove and inspect the plunger and spring assembly. Check for rust or fouling of the parts and inside the tube.
Check the tube for dents that can limit free movement. The spring SHOULD have a "kink" in it. This is to prevent the spring and plungers from popping out and getting lost.
With all other parts out install the safety and check for free movement with a positive "snap" but not too difficult.
Install the trigger, sear, disconnecter, Series 80 levers, hammer, and the sear spring. Slide the mainspring housing up on the frame until it puts pressure on the sear spring. Then install the safety.
Looking through the frame openings check for proper engagement with the rear face of the sear.
The safety MUST seat firmly against the sear to prevent any movement when the trigger is GENTLY pulled with the safety "on".
However it shouldn't prevent free safety movement.
A replaced safety is very often mis-fit and can be to tight, or so loose the sear can move with the safety on.
Try putting a dab of grease in the hole in the safety where the plunger seats. This may reduce the stiff operation.
Since the trigger was replaced look for an over-length trigger that may push the sear and disconnecter too far to the rear causing safety problems.
If the trigger has a trigger stop, BACK IT OUT or better yet REMOVE IT.
Trigger stops are notorious for causing problems.
If you want it, backing it out will eliminate it as a problem. You can properly re-adjust it later.