After 13.5 years and 120,000 miles, the hydraulic piston hood support in our RX400h finally decided to give up. Here's what I found:
1. The OEM replacement at the local dealership is $125.
2. Aftermarket ones are $13 - $18, depending upon quantity purchased.
3. Unfortunately, the OEM support is pretty much permanently attached at the lower end bracket and the bracket itself is not readily available. I did find one at a Lexus parts website but the Lexus part number listed was for a rear hatch bracket, and its photo did not look like the one I have. Thus, the aftermarket replacement appears to be a bust. I tried removing the OEM mount from the bracket but it seems the only way to free the ball socket from the bracket's ball is to use a cutoff saw/Dremel disc. Even then, you may damage the bracket pivot ball. I do not advise doing this unless you are well-experienced.
4. The OEM replacement comes with the bracket, The online price is about $75 + shipping. This is what I had to buy after returning the aftermarket supports. (I had bought a 2-pack for $25.)
5. While the OEM support is not assembled to the bracket, its lower pivot ball snaps in fairly easily. Here're the steps required to do the job, assuming you bought the OEM "kit":
a) Remove the two engine bay plastic covers - one over the battery and one closer to the firewall. This will allow you access to the support bracket screw.
b) Have someone hold up the hood while you use a small flat blade screwdriver to pop out the support's upper pivot socket retainer clip. You don't need to completely remove it - just pull it towards you a bit. If you get carried away and cause the clip to fly off in a dark corner of your driveway or garage, you can always use the old one.
c} Swing the support down and remove the lower end bracket's screw with a 10mm socket and ratchet wrench or box end wrench. Be careful not to let the screw drop down into nevernever land. Place the old support assembly away from the engine bay.
d) Pop the new support's lower pivot socket (the one that has no retaining clip) onto the new bracket's pivot ball. Install the bracket and its screw, and then back out the support's top pivot socket clip as you did to the OEM's clip.
e) Pop onto the upper pivot ball, the support's pivot socket, reinstall the plastic covers, and lower/raise the hood a few times to verify proper operation.