For outside, you are best with black foam dielectric (as opposed to air spaced).

If the aerial has been in place for a long while, you may find the terminations are beond re-use, and a new aerial may also be required.  I would get yourself a new aerial just incase.  Count the elements yours has already, and then look on the net to find out which aerial group you are likely to be in.

Take a look at our affiliated link "Satcure" at the top of this forum.

My link was more for the forum and advice.....

If you are comfortable up a ladder I'd give it a go. You can look up what sort of aerial you need for digital here. If it says "Amplified extra high gain" or something like that then perhaps get a professional in.

http://www.wolfbane.com/cgi-bin/tvd.exe
but ideally cross check here to see if it's the same group as the analogue
http://www.wolfbane.com/cgi-bin/tva.exe

If you don't understand the results tell us your full postcode.

The type you have can sometimes be identified from the colour of the bung on the end of the aerial.

Bung Colour Aerial Group   Red A (21-37)   Yellow B (35-53)   Green  CD (48-68)   Brown  E (35-68)   Grey  K (21-48)   Black  W (wideband 21-68)