I have never baked or repaired a crystal but the articles I’ve read say to follow the processes described below.  Most of the crystal cleaning instructions apply to crystals that can be disassembled, like FT-243 types.  The more modern packages are sealed.

First Steps:  Of course, if you have a second crystal of the same frequency, try that one to be sure the oscillator’s circuit and mechanicals are working properly.

Before baking or repairing a crystal, be sure the crystal’s pins and the socket are clean and making good contact and think about a repair rather than a bake.

Clean both the pins and the socket with Deoxit.  Then plug and unplug it several times to be sure the pins and socket mate properly.

Check the voltages on the oscillator tube to be sure they are correct and substitute another tube if possible to check for oscillation on the affected band (especially if it is a 6C4 or if it is high frequency).

Also, inspect the crystal wiring to be sure no connection is broken or poorly soldered.   Finally, clean the contacts on any switch the crystal is connected to.

Then turn on the xmtr and see if it will oscillate now, before proceeding to the Repair or Baking process.

Repairing a Crystal: You can also try to fix a “dead” or sluggish crystal by opening the holder (if it’s one that can be disassembled) and washing the quartz slab and the metal pressure plates with denatured alcohol.

As you disassemble it, carefully observe which side of the pressure plates that hold the crystal actually touch the quartz plate.  Usually only one side is ground and polished to precisely contact the surface of the crystal.

Reassembling with the wrong side touching the quartz plate usually results in a sluggish crystal or no oscillation at all, or a large frequency error.  This repair information is courtesy of Don, K4KYV.

Baking:  Lay a piece of aluminum foil on a cookie sheet and place the crystal on that.   Preheat the oven to 375 degrees F, then put the crystal/baking sheet on the middle shelf and bake it for one to two hours.  It won’t hurt if the crystal is in the oven while the oven is coming up to temperature.

Be sure to have a reliable oven temperature gage – if the oven temperature overshoots, the solder in the crystal might melt and ruin the crystal.

How long is best?  Depends on the crystal.   My guess is that if it’s a big FT-243 type, two hours might do it.   A little HC6/U might be happier at one hour.

If the crystal is truly not working, you can’t lose by trying to rejuvenate it.  The baking procedure can be repeated several times if desired.