[mythtvnz] No longer able to get lock on SBS... dish upgrade recommendations?

[Matt Poff]

Hi,

After a few months of fairly consistent SBS access  its dropped off  
completely for about the last fortnight. I've got a 70cm dish mounted  
on the roof with a 5dB gain LNB so I went up on the roof and tried to  
tweak skew direction etc but was still unable to get anything more  
than Freeview for which I'm getting these kind of figures in dvbtune:

Signal=48637, Verror=0, SNR=47580dB, BlockErrors=0, (S|L|C|V|SY|)

At this stage not sure what the options are to try and get SBS back.  
Is it worth looking at a larger dish? Something like this one: http://www.satmax.co.nz/Products/1200m(2006).htm 
.  This mount for the dish I have has pretty much rusted apart  
(particularly the vertical alignment) so also interested in any  
recommendations of dishes with high quality anti-corrosion mounts. I  
gave the current one several spray coats of zinc before installing but  
its on the way out now after about 3 years.

The position of our house means the line-of-sight  of the dish grazes  
a ridge-line - I'm wondering if increasing its elevation by a foot or  
two has much chance of improving things?

Cheers,
Matt