Quick check to see if you are getting voltage to the track? Do the lights come on with either loco?

The br18 is from the 35 series, so is analogue with a five pole motor, should run really nicely when you get it operational.

Try gently moving the wheels to see if they are free. It's quite common for a loco to get gummed up with old oil if it has been sitting for a long time. If this is the case it may require a strip down and clean out of the motor and gears, or you may get away with a drop of lighter fluid or IPA on each end of the motor armature to dissolve the old oil. Once it's moving it can be given a drop of new oil.

Hi Brett
Welcome to the forum. Obviously you have voltage on the track
The old loco is a 3000. It is pretty indestructible. It opens with a screw located on one of the domes
My best guess is that the slider got bent or damaged. Check also if the slider is tight (there is a screw).

On the other loco 3518: it is a 5 star traction (non-digital but smooth acceleration, deceleration) Did you have a demonstration when you purchased it. It was manufactured between 1988 and 1992 so if not used during all this time, you need to check if the motor / gears are not stuck. On this loco, one of the domes is plastic and removable. It hides the one screw needed to remove the case.
First make sure it gets power: does the lights turn on? Don't leave the power on long if the motor is stuck it may damage it after 10 seconds or so.

Another possibility is after a long time, the brushes do not make contact with the motor so push gently each of the brushes with a pencil to see if it starts rotating.

Cheers
Jean

Thanks guys will do