Yesterday I noticed that when my garage door is closing it stops mid way, hit the remote, it came down about a foot or two short of closing, hit the remote again and it stopped at say 2 inches above the ground and the last bit closed it. Well when I check it I don't see anything amiss as such I can point to. I always lubricate the garage door system - chain, rail, wheels...in summer with lithium grease, make sure the laser pointers are in proper place, see if there's any thing out of the ordinary, etc. This is the first time this has happened. The house is 20 years. We have been here for at least 8/9, so the unit is at least that old and pro'ly more. I am handy around the house but I have never had to do anything with garage doors. I would like to look into the issue before I have to call in a pro, if so. Is the unit starting to reach the end of life or is it something that can be repaired?

It's a craftsman 1/2hp

P/S
If there's any info you would like to know that will help with an answer please let me know.