I've never opened one of these newer quartz, but there can only be one way to remove the cap---the hard way (!). At least the earlier clocks (with mechanical movements/metal knobs/metal case as on 60's cars/Mangusta) used a screw on the front but had a keyed shaft to remove the knob-- I will not be surprised at all that these later ones were glued down. My suggestion is a soldering iron: place the clock face up, heat the shaft and when the glue softens pull the knob. Same process as a vintage guitar tuner knob... There really must be no option to this.
As well, replacing the bezel may be really hard here---at least for the other big gauges, the bezels went to very thin aluminum when the cans themselves went to plastic. I've seen guys on Ebay who have restored the plastic-can clocks, but must require a LOT of patience to work these apart...Lee
