Can I use Solo 401(k) as source of funds to pay 25% down and leverage debt for remaining principal amount to purchase a duplex that I will owner occupy and rent the other unit?  

It's highly unlikely, if not impossible, to find a traditional lending source to fund the purchase of tax deed property. 

I have been trying to source properties by calling on agents to ask if they have any off-market opportunities, however this isn't returning the response I had hoped. 

Referrals are my ideal source, but sometimes people can be hesitant about sharing their best vendor with you for fear you'll steal their vendor's attention away from them. 

However, sourcing your deals off-market should also be considered if you intend to flip full-time.Regarding sourcing deals directly from the seller, you can explore SEO, direct mail, cold calling, and anything that gets you in front of motivated property owners.

What a wonderful source of information, so looking to tap into all this knowledge.  

As a company we help investors with: - Sourcing properties in areas that should appreciate, have lower vacancies, and higher room rates based on our data from current properties.- Starting properties from the ground up with our expertise in what is needed for a rental to last and run smoothly, from simple furnishing to complete remodels/renovations.- Running properties as the businesses they are meant to be.

Our top source for applications is Zillow and we pay to get more exposure on Zillow, so if you aren't doing that, check into doing that.

Please help me with any source of knowledge that helped you or even steps to starting.

The builder says it is fixed (the builder patched the roof, replaced a tile, dried the walls using fan), but the leak detection test still identified elevated moisture levels in the walls and they couldn't pinpoint the source of the leak (There was no leaks in the pipes)