riggs 1977

T reg Seat Arosa 1.0i Hi All, On my way home from work yesterday and alternator belt snapped. Car made a funny noise for couple miles before that. Thought it a bit strange for belt to 'snap' so suddenly so investigated condition of pulleys and tensioner. Looks like tensioner is very rusty and does not turn smoothly plus bit of lateral movement in it. Ordered a new one through Sheppards VAG parts desk and will pick up tomorrow. Has anyone changed one of these and is there anything to watch out for. Looks like there could be spring tension and a pin that releases it. Want to gather a bit of info on this before I march out into the snow and lay on the ground for 2hrs sussing it out. Any info will be greatly appreciated! Thanks.