binding rear brakes on TF

My 2003 TF just passed its MoT (good!) but garage advised me that the rear brakes are binding slightly - I suspect lack of use - what's the best way to cure this, please (apart from using it more!!) 

Don’t spray with WD40! Do the job properly. The hand brake mechanism gums itself up inside the calliper & the spring won’t return it to the rest position.
How good are you on the spanners? When we find that out we can home in on your best course of action.
M

Reasonably capable - e.g. replacing bake calipers and bleeding the system

Those rear calipers are not difficult to work on. They are used on other vehicles.
The Tester will have seen on his screen for the rollers that the brakes were dragging before he even applied them.
In addition to checking the handbrake cables as mentioned above you need to remove the caliper and clean the pins and the sliders. 
You also need to check the piston. Do one side at a time. When the caliper is off lightly press the brake pedal so that the piston moves outwards. I use a big pair of adjustable grips that go around the back of the caliper with one jaw and the piston with the other to push it back in again. If it doesn't want to move freely just spin it a little so you rotate the position. You dont have to move it much but it breaks the friction but it does Not break the seal.
Rotate it 15 mm or so then rotate it back it doesn't matter. Then it should push back in easier. You can buy cheap clamps that you can push the cylinder back in with.
Having freed the piston after applying the brakes on release the piston should receed back a little. A sticking piston won't do that and constantly applies light pressure to the pads...and you have a warm wheel.
Clean up the slots in the caliper where the top and bottom of the brake pad sits and lightly apply anti seize grease, Coppaslip or similar.
I'm sure you will be able to fix it yourself, you don't interfere with the fluid it's just straight forward stuff. 
Good luck!

You can refurbish the rear callipers but honestly the most effective permanent way to fix the issue is to buy a new set of callipers. Last time I looked they weren't that expensive.😎
Here you go, 79 quid a pair!
2x Brake Calipers Rear for MG MG TF 02-09 MGF RD 95-02 1.6 1.8 SMC000470 / 460 Buy It Now

If it’s the destination you are looking forward to & not the journey, then David’s advice is spot on. The down side is you will have to bleed both sides.
Every silver lining has a cloud.
I would be spending an hour looking at the pistons & checking the handbrake action to make sure that the spring is returning to its stop peg. There is a roller bearing which guides an eccentric within the calliper body, it’s behind the grommet, behind the actuator, behind the spring, behind the nut. What a happy family.
Water gets in here, the rollers corrode & collapse.
Normal service can be restored for a short time, if this is the problem, if you give it a squirt of WD40 (the sperm of satan), this action is counter productive in the long term & only accelerates the buying of replacement callipers.
M

Totally agree about WD40! It has its uses but watching somebody spray it on to two load bearing surfaces for lubrication annoys me!

Thanks all for your advice - I'll get on to it in the next couple of weeks

I wonder if a silicone based spray lubricant may be better than WD40 ?

Only when you take the rear callipers back down to their vest & underpants do you fully understand how they work & unless you have the correct tools to rebuild them you’ll be wanting replacements.
The chamber in which the needle rollers live is originally filled with a specific grease & over time this degrades & water gets in, turning rollers into rust dust. If you squirt any type of spray “oil” in you create an rust/ lubricant paste, this dries out rapidly & solidifies exacerbating the problem further.
Prior to the squirt of death some of the rollers remain in place by dint of the rust around them, wash this out & you have a problem multiplied.
I’ve no doubt that many folk have been squirting there callipers (not a euphemism Cobber) & getting away with it but eventually - - - - -
M

Hearing what Im hearing I would definitely go for new callipers in this situation. £ 79 a pair is very reasonable for brake callipers.

@Airportable

You always give sound advice that comes from experience as do other long time enthusiasts on this site and as my car is long term I devour it up!
Not to mention your wit..not at all...but it does crack me up!