This is also a good time to make sure you have the appropriate bulbs in your tool kit for replacement should it become necessary on the road. Inspect the bunks for wear on the carpeting or on the rubber padding that is beneath the carpet. Some trailer boaters spray a silicon coating on the bunks to make the surface easier to slide the boat on and off. Roller should be turned individually to determine if any have locked. Inspect the rollers for wear and remember when it comes to rollers that are worn, there is no time like the present to replace them.
Poly rollers last a lot longer than their rubber counterparts.
Inspect for wear and check the S hooks for possible bending. It is a good idea to replace the S hooks with screw-pin shackles that have a wire running through the pin's eye. It provides a connection that is considerably more reliable and solid than S hooks. Inspect the grease in the hubs. There is no time like the present to replace the grease, especially if the trailer has spent a winter outside in dampness.