The next steps require a bit of bravery and acceptance to modify the covering
- the cloth is quite flexible, but there are MANY velcro strips sewn to the fabric and these velcro strips make it almost impossible to strech/fit the fabric around my new insert. They are sewn to the fabric, and make it completely inflexible to stretch when trying to insert the new pieces.
- so, many (most) of the velcro was removed by cutting the stitching. Much of it is saved for later as you will see. In reality, there is not such a need for so much velcro to attach it to the seat, anyway.
All the items were squeezed into the covering, but of course the added thickness creates an issue. I have simply stretched the fabric as much as I dared, then strung velcro pieces (reused from above comments) across the back to keep it together. There is of course a gap in the material , but is no issue for me since it will not be seen. There is still some of the original velcro (sewn to the fabric) near the top of the insert (left side of the image) that clings to the back of the seat/bucket when inserted. So it's still held in place even if there's not as much attachment as there was before. There is still more left-over velcro I can use to secure it to the seat/bucket at the lower levels (right side of the image) if needed, but I'm pretty sure it will be fine as it is.
Here it is from the top, and looks quite OK for me. Fabric has stretched and fit just fine from the business side.
Quick test fit, and it seems good. I was originally thinking I'd need to get a new covering made/sewn, but at this point I'm quite happy with the result I have.
DEFINETLY much more support to the lower back. Time will tell if there are any other issues with this, but so far it is much better than before.
Next is simply to reconnect the leads from the amp and have fun.