The security gate on our home has got a problem, the gate slider wheels have broken. Is there somewhere that can provide replacements or will I have to get a completely new gate?

Try Far Eastern Supply on Sukumvit road they are close to the PTT station near thenew entry ramp to highway 7, they close at 5pm take the pictures with you to show them what you need.

These look like the Haffle sliding door gear sets. I bought a set a few years back, they were around 800baht for the wheels part but the stainless track was expensive if I remember correctly.

In any event both parts are available at HomeWorks

These are the same as the simple tracks they use for hanging mosquito doors, any of the shops along Sukhumvit that supply aluminium sections to the screen makers will have the track wheel sets.