murphimurry and sean(pretty sure) from xd had some pretty cool tricks to help with this.
There’s a couple things I’d try. Firstly, I would consider upping your solvent:oil ratio to make sure there is enough solvent. Make sure it is at least the same butane:oil that you’d normally run at, going a little bit higher might help.
Second thing you can try is putting some material socks down to act as a sort of filter/sponge to absorb the thicker oil until fully dissolved- this will help prevent the heated oil from cooling inside the bottom line/manifold depending on your set up. Along with this, adding a heating element to any lines/fittings outside the jacket on the bottom of the collection will help as well.
The last 2 tricks are and/or injecting butane/nitrogen from the bottom. If injecting cold butane, I’m not sure how much pre heating the oil will help, may actually work against you by allowing it to flow into the lines/fittings that aren’t jacketed then harden when butane is injected. Either way, once butane and oil have come up to temp, recover some butane vapor and inject nitrogen from the bottom. Or slowly bubble nitrogen up from bottom to create agitation while solution comes to temp.
Another thing that works is just injecting butane then allowing room for vapors to leave vessel so as it boils it creates agitation. This doesn’t work very well with cold butane in my experience, the cold butane will instantly solidify whatever oil is in there then you have to allow enough time for it all to come to temp. Leaving vessel open or closed for vapor to escape works, couldn’t tell you which is faster as I wouldn’t say either method involving cold butane is fast(not to mention energy efficient). If leaving vessel open you have to monitor how much butane is recovered to make sure your ratio is still correct.