One of the biggest causes of failure with these things comes down to connectors - if you're a handy type with suitable sign-off you could slide the unit(s)out & clean what connectors you see with a rubber and/or suitable cleaning fluid, slide them back in & test. It could well sort things out so it'll last through 'till your upgrade.
If you're not able to do it yourself I'd certainly ask an engineer to try that for you before you contemplate much else.
FP.