Rainsoft has a lifetime warranty on the resin tanks. The only charge is the service call fee (about $115 - $150). I have had my Rainsoft system for about 12 years and recently had a problem with the resin beads leaking from the membrane. The water pressure in the house went to almost nothing, all faucets, showers, toilets, etc. I had a plumber come out, and he found that my PRV (Pressure Reducer Valve) was full of resin beads. Aha! Resin beds could only come from one place, Rainsoft.
The Pressure Reducer Valve is installed in the ground and controls the water pressure coming in to the house. The water pressure from the city is about 130psi, which is way too powerful for a house to handle. So, most homes have a PRV in the ground (completely unrelated to Rainsoft) that sets the water pressure at 70psi. Since the Rainsoft Resin tank was leaking, the resin beads got caught in the PRV. Since the PRV was clogged with Resin beads, the pressure in the house went to almost nothing. There are a couple of ways to resolve this issue.
The quick way is to use the "Bypass" switch on the Rainsoft system. Then, shut off the water at the meter (from the city), and clean out the PRV filter. In my case, I had to turn off the water at the meter, clean out the filter, turn the water back on at the meter, open all faucets and showers in the entire house including outside hose fixtures. Then, turn the water off at the meter again, clean out the filter again. I repeated this process about three times, which is about how many times it took for all of the beads to get pushed from the resin tank and fill up the PRV again (whatever beads were left in the line). Since the Rainsoft system was bypassed the whole time, no more new beads would come in to the pipe. This is the quick fix. Leave the Rainsoft system on Bypass and clean the PRV filter. Now you should have good pressure in the house.
Secondly, long term fix. Contact Rainsoft. You need to replace your Resin Tank. This is a lifetime warranty item, so they will replace it for free. Unfortunately, free doesn't include the service visit. Once the new resin tank is in place, you already have the PRV cleaned out. Turn off the system bypass and you are good to go.