i like the blue revell contacta or humbrol poly cement in the bottles with needles. the humbrol is probably my first choice as its slower flowing than the revell, but they both work well.
if its a slightly off white crystaline residue its just dried totally awesome. stick it back in for ten mins then scrub it in soapy water and it should come off. i like the totaly awesome cleaner as its safe to strip resin in unlike others