Take a dig into where the bag is leaking= Commonly its the rubber flexible line where it goes into the bag.
There are online Instructoins for DIY home repair of bags.... Inlcuding using a hydrolic line shop to crimp lines made up for your need.

 In short=   cut off the nipple of the bag ( where the flex rubber line attaches to the bag)
  Tap the bag for a nipple fitting. 

Have that nipple fitting crimped into a new hydrolic line. that has th eother end also crimped to the original british fitting.

 In short you're re building the hydro line that fails.

So I redid the hydro lines in 3/8” copper, replaced the valves and pumped up the system. The morning had finally come to drive the car for the first time. I opened the garage and the right side of the car was on the ground. I had the bonnet off so when I went to the front say the braided line to the bag was no longer attached to it. There was lack liquid all over the garage ceiling. Sad day. 

Anyways, I’m weighing my options here. I’d love to convert to coil springs but that’s not in the budget right now. Would you have a bag for sale? It might get me through the summer. I’m in Sebastopol CA 95472

Well I said F it and redid the rigid lines, I have parts coming in the mail so I can pump up the system (hopefully in the next few days). 
As for the age of my car and the hydro system on it, I’m sctratching my head a little bit with it too. It has everything a Cooper S came with but Cooper S didn’t start until 63? 120mph speedo, oil cooler, 7.5” discs, extra studs in the head. It has a 1275cc engine and I know that didn’t come until later. 

my boot lit has a year stamp of 66, wiper motor is stamped 60. I’ll have a look at the glass and dimmers to see what I come up with. 

Welcome patrick,

A few quick places to get a better idea of the year of your car are on date stamped parts such as the wiper motor, trunk/boot latch, glass, head lamp dimmer switch, dash switches, etc. For more detail look up past forum posts.

I've used copper lines with great effect, and normal off-the-shelf compression fittings too when joining them.

One thing to be wary of though - to go from wet to dry is easy, you just modify the spring seats to accept cones instead of bags, change (or modify) the top suspension arms at the front to accept a shock absorber, fit front damper mounts, and change the rear arms (or stub axles) to again allow for a damper to be fitted.  Going the other way is (if I remember right) a lot more difficult - you'll need new front & rear subframes and plumb in the hydro lines (and fit the pipe retaining clips) while they're off the car, but more importantly you'll need to drill big holes through the front bulkhead crossmember to allow the hydro flexi pipes to come through !

It may not be a '62 is what I'm getting at...

I know nothing about hydro cars.  The following information is just hearsay from me.

On some of the U.K. boards there have been threads discussing replacement hydro lines.  I don't know if anyone in the U.S. sells those kits.  You may want to consider ordering from Europe if necessary.

The pumps do show up every now and then.  There are also ways to improvise pumps.  Browse the Austin America website (link below) for some information on the hydro system and how to fill it.  (Click on tech advice in the left column then follow the links on the next page that opens).
//www.austinamericausa.com/

EDIT:  Also see the currently running thread linked below discussing hydro pumps.
https://www.minimania.com/msgThread/125744/1/1/Hydrolastic_Pump

Thanks guys, I’m going to have a go at replacing the rigid lines and testing the bags. I was told when I bought the car that the suspension had been changed. 

hopefull I can get my hands on a pump afterwards. 

I'm beginning a slow roll toward selling off everything I have mini related. Plan is to keep CTR/ALEX, the Moke and maybe the 64 1071.
The balance of my 5500 Sq Ft of mini parts needs thinning down. Not to confuse I don't plan to give it away. I paid a little something for everything I have.

Two more car guy friends have passed away since the fall. Helping their widows sell off their parts got me thinking. I decided to not buy but to alert others and help set fair values. Steve (CTR)

PS I have some hydro stuff but no idea where you are located.

Interesting.  Hydro didn't come in 'til 1964.

But to be more helpful, if the pipes are rotten, the displacers ( hydro bags) are probably scrap too, and are very expensive (tho there is a company in the UK that repairs them).

So consider reverting to dry suspension - much more relaible - and period correct if your car is a '62.

If you fill in your profile so people know where you are located, that would help folks who might be close enough to you to help.

Hey there, I’m new here and just picked up a 62 Cooper project last week. The rigid lines in the hydrolastic suspension are rotted out and broken so the car is on the bump stops. Has anyone used a roll of soft copper to re run the lines? What size is it, 3/8”? Also, is there anyone out there who would loan or rent me their modified grease gun to fill my system after it’s been repaired? 

This is my first Mini and I’m super excited about the project. 

Patrick