To be blunt, I wouldn't recommend repairing it at all.
Pioneer plasmas are regarded as the most complicated tvs ever manufactured. They stopped making tvs 4 years ago, there are very few techs that will work on them any longer, and parts are difficult to get. Assuming both were available, you'd still be spending $400+ to have this fixed, while you could buy a brand new LED tv (plasma is now obsolete) with updated features and a fresh warranty, for $300.
As an alternative, you could instead disable the tvs internal speakers, and hook up an external sound system to it, anything from a basic $100 soudnbar to a full scale surround sound system, either of which will give better sound and can also bused with a future tv when the pioneer eventually dies, which could really be any day now as it is already far past its designed service life.
Depending how you’d like to proceed here, I can help with finding parts, finding a repair shop, or recommending replacement options. Just let me know.
Best regards, ***** ***** for the news,
I am an independent technician and I've spent my personal time, unpaid, in an effort to assist with the question for which you solicited my services. This site works on the honor system, and to that end, I have prioritized working with you ahead of other paying customers.
Although you’ve already paid your fee to the site, I am only compensated for my efforts when customers such as yourself leave positive feedback for my work. Again I apologize there is not a better outcome here, though this is really beyond either of our control. I do hope you’ll consider leaving a 5 star rating for me, rather than “shoot the messenger”, so that I may get credit for my time spent in good faith to answer your question accurately.