Manual Channel Tuning Problems

[Wills13]

Hi all, first time here, so please excuse if I stuff up.
I have 2 32" TV's and a 55" Panasonic Plasma that is giving me a hard time.
Until recently all channels worked great no interference or anything, both my 32" TV's are working still perfect all of the same Antenna at  around 15 year old digital Hills Antenna.
I have lost Channel 7, Channel 10, and ABC,  SBS, 9, and 32-31 are fine. I have tried a new lead from the wall socket to the TV I have done several Manual Digital Tunes going by the the data from the Technical Information for Melbourne for Frequency and Channel.
Channel 7, 10, and ABC are in the red in both strength and reception.
Would a new  "Hills True-Band Metro Plus (Black Arrow)" Antenna be worth a try, or do I just need a Tech Expert.
Any advice will be greatly appreciated
Wills13