I have an old Humax PVR-9300T box. When new channels start I used to get a message telling me to re tune my box. But last year a couple of channels appeared with out me having to do this. Now I hate having to re tune my box as all the shows I have set to record have to be put back in again. A while ago the Syfy channel started on Frieview and no message telling me there was a new channel and to re tune and it wasn't just suddenly there like a couple of other channels. I went to channel 31 to see if Spike was there last night and it was still 5USA. What's up with my box as I'm sure some channels have just appeared. Should I just do a re tune as my box has stopped telling me there are new channels or what?

Some new channels - even though they are only standard definition - are broadcast on the DVB-T2 mux that carry HD channels. The PVR9300 has a DVB-T tuner which cannot pick up those channels.
Some 'channels' (around LCN220) are pointers to an internet stream and can only be understood by receivers with spec 'Freeview HD+' (basically smart TVs).
Some channels are broadcast on a lower-power 'local' mux, and you would need to be in range (ie. in a densely populated region) to receive these.
As to whether the basic five DVB-T mux have any new channels, the most recent I found is Horror at LCN70. If you don't yet have that, consider doing a full retune despite the rigmarole involved (a manual search is best, as you can remove unwanted channels - ie. those between 201 and 600 and any with the encrypted flag - before saving the results of each mux search).

I'd suggest making a note of any planned recordings, as usually on both the Humax PVRs I've got, including one of the more recent HD varieties, you will lose them when you do a manual channel update.

There is a facility in the Custom Firmware for the HDR Fox, to backup and restore the scheduled recording list, before and after a retune,

A simple good tip from a friend of mine that works well, take an off screen picture of your record schedule using a digital camera or phone.

Thanks all.

I must have just been lucky with my Humax Foxsat-HDR as I did a Manual Tune and a Freesat Tune without losing my planned recordings. I had written them down just in case, but I like the tip of taking a photo instead (even though that wouldn't tell you which channel they were on)..