Yes sure we can replace your slider ... you've been into our shop before ... 
Check
  1. Are all the zip teeth still OK?If not need a new zip.
  2. Do we stock this slider size? Otherwise need new zip.
  3. We do not stock any opti sliders. New zip.
  4. I'll just check that we do have a slider that will fit...
footcom.co.nz/?s=slider&post_type=product

Main steps

Slider replacement from the top
If you can easily get at the bottom of the zip then do it that way.
1. Select new slider
​2. Unstitch top corners
​3. Remove old slider
​4. Back on new slider
​5. Replace top stops
6. Glue zip ends back in 
7. Stitch
8. Check

Main steps explained
​

1. Select new slider

Click to set custom HTML
The main slider we replace is a YKK coil zip size 5 Locking slider, 4mm wide per side of zip. This is found mainly on boots and shoes.
​The second most common is very similar but is non locking and found on bags.

2. Unstitch top corners

Click to set custom HTML
Straighten out tail of zip ends and remove top stops. Unpick as little as possible to get the job done.

3.  Remove old slider

Insure the zip stays done up completely as you remove the slider, especially at the top. You may need to give the existing slider a gentle squish with pinchers to make it work.

4. Backing on new slider 

  1. Make sure zip teeth are together at the end
  2. Note which side has the last tooth (right side for this example)
  3. Back the slider on as far as it will go
  4. Pull tag out to disengage lock
  5. Gently pull apart the zip
  6. Wiggle slider to the  left and back to the right to get it started

Still having issues
  1. Poke a needle down inside on the right to start the zip coming apart
  2. Cut another 2 teeth off the short left side, now it will be real easy
Practice on an old bit of zip

5. Replace top stops - if any

Hold topstop  with long nose pliers and push onto the zip from the back. Lie flat on glass, fold the 3 little legs over then tap it on the last to finish.

6. Glue zip ends back in 

7. Stitch

Polish

8. Check
Check the slider stops at the top stops. If necessary, stitch across the teeth at top.

Misc

Normally Metal zip sliders only go on from one end only. There are some that go both ways but they arent much good. Take a good look at the teeth and compare to a new metal zip in our zip stock.
No you cannot use a vislon slider on a metal or coil zip.