Finally found a hydra mini dedicated game , sometimes called hydra cabaret.  I was looking for almost a year.  ( Some have said this is not a cabaret,  however Atari did call it a mini cabinet on the brochure)
I knew it had a few problems but didn't realize the challenge until it arrived.

The seller said it was in mint shape but was willing to sell it at a discount because it died
after a move.

The critical item on this game is the plastic bezel and monitor plexi which cover most of the front of
the game. I  was assured it was in very good shape but had a few "chips" I asked for pictures.

It didn't look too bad at the top and appeared that it might be possible to make up a patch that could be
painted to match and be fairly invisible. Pictures can be deceiving.

No mention was made of the fact that the coin door was stripped as well.
 

First thing was to remove the front bezel to get a closer look at the damage and decide how to proceed.
I decided the only way to fix this would be first to repair and reinforce the cabinet on the inside. Then  filling  and shaping the  areas that were missing. Finally painting the plastic to complete the repair.

First a super glue formulated for plastic (Devcon Grip-Ton-ite  #30350) was used to "weld" the broken seams and cracks back together. Next an epoxy material made by BONDO to repair plastics was used along with fiberglass mesh to create both clamps that would keep the cabinet together and also fill any voids. I used fiberglass mesh normally used for spackling since it had adhesive on it and was easily formed around the irregular surfaces on the back of the bezel.
Additional fiberglass was used in some areas suspended in the epoxy to make it even stronger.

Once all the areas seen on the external surface were shaped to match the cabinet the final step was to paint it.
Here is where Krylon's new Fusion spray paint worked great. I can't say too much about this product.
Before even attempting this project, the first thing I did was test this paint on the inside of the bezel. After being convinced it would not damage it and would produce a nice finish I went forward.

BTW it  took about 40 minutes to polish out the big X on the plexi.
 
 

I also didn't mention or show the cigarette burns and melt marks that were present by the boost buttons.
They were sanded and filled as part of the restoration.

Those that are sharp will notice that the marquee is NOT factory. Mine is terribly discolored and has cracks. The one on the game  is a temporary one I made up until I can find either a NOS original (anyone know of one?) or I can at least get a fellow hydra owner to scan a  clean original.
 

Next came resolving issues with the game.

Turned out the mint game also had some technical problems as well.
Intermittent power to game.
Wiring in "flight" yoke hacked up.
Signal for DOWN not making it to the board per diagnostic test NOT related to hacked wiring.
Boost buttons not lighting when boost credit present.

The yoke was rewired using 3 conductor microphone(stereo) extension wire found at radio shack (20 ft. $3)
Each pin was carefully removed from the connector and the wiring attached and reinstalled in the connector.

The down signal not getting through was caused by a bent pin in the jamma connector.

The NO boost button light problem was traced to a buffer transistor on the game board Q4. You can not use a regular
transistor for this. It is a darlington.

The intermittent power to the game is  what you might expect ....a bad cord!

Rebuilt Coin door replacing missing and hacked parts

Repaired damaged base and installed new t-molding on it.
 

Things left to do at the time of this writing -
Though I made a new marquee I want a clean original or better
a NOS original , still looking.
If you have one or know of one please contact me.