Can anyone tell me how to change a handbrake cable on my Carisma, the handbrake seems to be holding only one side, and the slack on the adjuster nut at the lever has been taken right up, but still not holding.

Did yu check to see if the side that is not holding if the primary shoe that the handbrake cable pulls on is not overlly worn? If not yu may need to adjust the adjuster at the shoe. It may be too far retracter so when the handbrake is engaged , the shoe is not coming out far enough to grab the inside of the drum. There is most likelly nothing wrong with teh cable. Yu just need to adjust the shoes . When yu pull the wheel off and inspect theshoes , yu will see if they are overlly worn or not, if tnot yull need to use the adjuster , yull see it it will be near teh retainer spring , the spring will connect frum the top and bottom of the shoes to retract them. On the top side , where the upper spring is will be the mechanical adjuster , where yu can adjust out the shoes to make them grab accordinglly when engaged. Do not over do it cause it will make it hard to put the drum back on.