1970 Convertible Rear armrest panel vinyl crack repair

[colorado4x4]

I have a small crack in the vinyl on my passenger side rear seat arm rest panel in my 1970 Deville convertible. 
What would be some ideas and/or products to repair/fill in/patch it ? Once I take the window switch/ashtray panel out, looks like I could inject some sort of filler into the area on the back side of the crack. 

Also have a 2+ inch crack in the fiberglass backside of the driver side rear seat arm rest panel that I will need to patch also.

As every project multiplies into other additional projects, this is one of the additional project that started with my replacing the window arm roller and cleaning/re-greasing all the rear quarter window tracks/guides project.

[Clewisiii]

https://leatherworldtech.com/deluxe-leather-repair-kit/?gclid=EAIaIQobChMI_PHw6cSH7AIVZB6tBh0p7AogEAQYASABEgKN7fD_BwE

[Cadillac Fleetwood]

The fiberglass shell of the rear quarter trim can be repaired using the same fiberglass repair materials used on surfboards and Corvettes. These panels usually held up very well, and the breakage occurs  because previous attempts at removal  ignored the hidden retention screw behind the courtesy light, and the virtually hidden screw at the top leading edge. The resulting manhandling caused breaks and cracks.

These panel assemblies began with the fiberglass base, black foam padding was applied, and then the vinyl was applied, vacuum-formed with heat applied.  Cracks and splits in the vinyl are usually repaired using a clear or opaque vinyl patching compound (often requiring two applications),  a bit of finish sanding, and then a re-dye of the entire panel.  In prominent areas, a graining sheet is used, with heat, to apply a matching pattern to the patched area and make it as invisible as possible.

When I would hang out at Marvin  K. Brown Cadillac while my car was being serviced, I would wander over to the area where lease returns and trade-ins were reconditioned, and watched holes in leather, burns in carpet, and cracks in  vinyl being repaired a part of the reconditioning process.

My 1970 Fleetwood Brougham with a red leather interior required a repair to the passenger-side front door panel. It had a 5-inch, meandering "spider-web" series of cracks in the recessed area above the armrest.  It was the only blemish in an otherwise faultless interior. After 15 years of looking at it, I had a local trim shop with connections to a "mobile" vinyl repair person who made the rounds of the car dealers, repair the crack and re-dye the panel.

I removed the panel from the car, removed the carpeting, the door lock ferrule, and all the chrome and woodtone trim to make the job easier and neater. That was in 2000, and the repair remains invisible.

These panels are prone to the type of striations on the upper surfaces as shown in your first photo. They are sometimes straight, and sometimes circular, but in both instances are more of a challenge to repair than an open crack. A re-dye of the panel often reduces the visibility of these, but does not eliminate them entirely.

Often encountered in restored cars are re-covered panels.  I have not seen any re-covered panels , elaborate French stitching notwithstanding, where the quality of workmanship justified the effort, or that I would be happy with.  I would rather have a slightly imperfect ORIGINAL than a poorly done eyesore of a re-do, that does not, and cannot reproduce the "seamless" curves and welts.

Charles Fares